I experience the same problem described above by AZ with the newest Gutsy kernel (2.6.22-14.47, 18 dec 2007)
My setup (Dell Inspiron Desktop 531s) has been stable since I've upgraded from Feisty last month.
I mount three nfs v4 shares from a Fedora 7 server (from my /etc/fstab), and the kernel crashes at the same point. GDM executes but neither the mouse nor the keyboard works. The workstation boots fine when I comment the three NFS mounts in /etc/fstab.

From my /var/log/kern.log: 

Dec 19 09:17:27 apollon kernel: [   24.824000] bridge-eth0: enabling the bridge
Dec 19 09:17:27 apollon kernel: [   24.824000] bridge-eth0: up
Dec 19 09:17:27 apollon kernel: [   24.824000] bridge-eth0: already up
Dec 19 09:17:27 apollon kernel: [   24.824000] bridge-eth0: attached
Dec 19 09:17:30 apollon kernel: [   27.800000] NET: Registered protocol family 17
Dec 19 09:17:34 apollon kernel: [   31.980000] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000038
Dec 19 09:17:34 apollon kernel: [   31.980000]  printing eip:
Dec 19 09:17:34 apollon kernel: [   31.980000] f8c3a040
Dec 19 09:17:34 apollon kernel: [   31.980000] *pde = 00000000
Dec 19 09:17:34 apollon kernel: [   31.980000] Oops: 0000 [#1]
Dec 19 09:17:34 apollon kernel: [   31.980000] SMP 
Dec 19 09:17:34 apollon kernel: [   31.980000] Modules linked in: af_packet vmnet(P) vmblock(P) vmmon(P) ppdev ipv6 cpufreq_userspace cpufreq_powersave cpufreq_stats cpufreq_ondemand freq_table cpufreq_conservative sbs ac dock video container button battery nfs lockd sunrpc parport_pc lp parport snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device nvidia(P) xpad snd k8temp serio_raw agpgart i2c_nforce2 pcspkr psmouse soundcore snd_page_alloc shpchp pci_hotplug i2c_core evdev ext3 jbd mbcache sg sr_mod sd_mod cdrom usbhid hid sata_nv amd74xx ide_core ata_generic forcedeth libata scsi_mod ehci_hcd ohci_hcd usbcore thermal processor fan fuse apparmor commoncap
Dec 19 09:17:34 apollon kernel: [   31.980000] CPU:    0
Dec 19 09:17:34 apollon kernel: [   31.980000] EIP:    0060:[<f8c3a040>]    Tainted: P       VLI
Dec 19 09:17:34 apollon kernel: [   31.980000] EFLAGS: 00010206   (2.6.22-14-generic #1)
Dec 19 09:17:34 apollon kernel: [   31.980000] EIP is at nfs_fhget+0xd0/0x3e0 [nfs]
Dec 19 09:17:34 apollon kernel: [   31.980000] eax: 00000000   ebx: 00000000   ecx: f72f0674   edx: 00004180
Dec 19 09:17:34 apollon kernel: [   31.980000] esi: f72f0600   edi: f6b49bd4   ebp: f6b17128   esp: f6b49b88
Dec 19 09:17:34 apollon kernel: [   31.980000] ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
Dec 19 09:17:34 apollon kernel: [   31.980000] Process mount.nfs4 (pid: 6094, ti=f6b48000 task=f717c530 task.ti=f6b48000)
Dec 19 09:17:34 apollon kernel: [   31.980000] Stack: f8c39f10 f6b49bac 00000020 c0133462 c03d9de0 f6b17000 fffefa43 c02bd89d 
Dec 19 09:17:34 apollon kernel: [   31.980000]        00000282 f6b49c66 f6b49bd4 f6b49bd4 f72f0600 f6b49c64 f6b49d1e f8c388d7 
Dec 19 09:17:34 apollon kernel: [   31.980000]        f717c6f0 c1f07000 f72f0200 00000002 00000000 00000000 00000000 00000000 
Dec 19 09:17:34 apollon kernel: [   31.980000] Call Trace:
Dec 19 09:17:34 apollon kernel: [   31.980000]  [<f8c39f10>] nfs_init_locked+0x0/0x60 [nfs]
Dec 19 09:17:34 apollon kernel: [   31.980000]  [group_send_sig_info+114/128] group_send_sig_info+0x72/0x80
Dec 19 09:17:34 apollon kernel: [   31.980000]  [tcp_send_fin+125/320] tcp_send_fin+0x7d/0x140
Dec 19 09:17:34 apollon kernel: [   31.980000]  [<f8c388d7>] nfs4_get_root+0x177/0x260 [nfs]
Dec 19 09:17:34 apollon kernel: [   31.980000]  [<f8c3be71>] nfs4_get_sb+0x291/0x370 [nfs]
Dec 19 09:17:34 apollon kernel: [   31.980000]  [vfs_kern_mount+182/304] vfs_kern_mount+0xb6/0x130
Dec 19 09:17:34 apollon kernel: [   31.980000]  [do_kern_mount+63/240] do_kern_mount+0x3f/0xf0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [do_mount+1643/1856] do_mount+0x66b/0x740
Dec 19 09:17:34 apollon kernel: [   31.980000]  [tcp_v4_send_check+68/240] tcp_v4_send_check+0x44/0xf0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [tcp_transmit_skb+1017/2048] tcp_transmit_skb+0x3f9/0x800
Dec 19 09:17:34 apollon kernel: [   31.980000]  [kunmap_atomic+94/160] kunmap_atomic+0x5e/0xa0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [kunmap_atomic+106/160] kunmap_atomic+0x6a/0xa0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [__handle_mm_fault+1671/2816] __handle_mm_fault+0x687/0xb00
Dec 19 09:17:34 apollon kernel: [   31.980000]  [__mod_timer+159/176] __mod_timer+0x9f/0xb0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [do_page_fault+905/1680] do_page_fault+0x389/0x690
Dec 19 09:17:34 apollon kernel: [   31.980000]  [error_code+114/128] error_code+0x72/0x80
Dec 19 09:17:34 apollon kernel: [   31.980000]  [copy_mount_options+171/336] copy_mount_options+0xab/0x150
Dec 19 09:17:34 apollon kernel: [   31.980000]  [sys_mount+119/192] sys_mount+0x77/0xc0
Dec 19 09:17:34 apollon kernel: [   31.980000]  [sysenter_past_esp+107/169] sysenter_past_esp+0x6b/0xa9
Dec 19 09:17:34 apollon kernel: [   31.980000]  =======================
Dec 19 09:17:34 apollon kernel: [   31.980000] Code: d8 fe ff ff 89 44 24 14 89 54 24 18 81 8d 3c 01 00 00 82 00 00 00 89 5d 20 8b 57 20 66 89 55 6a 8b 86 64 01 00 00 0f b7 d2 8b 00 <8b> 40 38 8b 40 0c 89 85 90 00 00 00 89 d0 25 00 f0 00 00 3d 00 
Dec 19 09:17:34 apollon kernel: [   31.980000] EIP: [<f8c3a040>] nfs_fhget+0xd0/0x3e0 [nfs] SS:ESP 0068:f6b49b88
Dec 19 09:17:34 apollon kernel: [   32.004000] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000011
Dec 19 09:17:34 apollon kernel: [   32.004000]  printing eip:
Dec 19 09:17:34 apollon kernel: [   32.004000] f8c3b26c
Dec 19 09:17:34 apollon kernel: [   32.004000] *pde = 00000000
Dec 19 09:17:34 apollon kernel: [   32.004000] Oops: 0000 [#2]
Dec 19 09:17:34 apollon kernel: [   32.004000] SMP 
Dec 19 09:17:34 apollon kernel: [   32.004000] Modules linked in: af_packet vmnet(P) vmblock(P) vmmon(P) ppdev ipv6 cpufreq_userspace cpufreq_powersave cpufreq_stats cpufreq_ondemand freq_table cpufreq_conservative sbs ac dock video container button battery nfs lockd sunrpc parport_pc lp parport snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer snd_seq_device nvidia(P) xpad snd k8temp serio_raw agpgart i2c_nforce2 pcspkr psmouse soundcore snd_page_alloc shpchp pci_hotplug i2c_core evdev ext3 jbd mbcache sg sr_mod sd_mod cdrom usbhid hid sata_nv amd74xx ide_core ata_generic forcedeth libata scsi_mod ehci_hcd ohci_hcd usbcore thermal processor fan fuse apparmor commoncap
Dec 19 09:17:34 apollon kernel: [   32.004000] CPU:    0
Dec 19 09:17:34 apollon kernel: [   32.004000] EIP:    0060:[<f8c3b26c>]    Tainted: P       VLI
Dec 19 09:17:34 apollon kernel: [   32.004000] EFLAGS: 00010202   (2.6.22-14-generic #1)
Dec 19 09:17:34 apollon kernel: [   32.004000] EIP is at nfs_compare_super+0x3c/0xe0 [nfs]
Dec 19 09:17:34 apollon kernel: [   32.004000] eax: 00000001   ebx: f72f0200   ecx: 00000010   edx: f6b16a2c
Dec 19 09:17:34 apollon kernel: [   32.004000] esi: 443e304c   edi: 00000011   ebp: f6b16a00   esp: f6b4fcb4
Dec 19 09:17:34 apollon kernel: [   32.004000] ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
Dec 19 09:17:34 apollon kernel: [   32.004000] Process mount.nfs4 (pid: 6099, ti=f6b4e000 task=f72cb9f0 task.ti=f6b4e000)
Dec 19 09:17:34 apollon kernel: [   32.004000] Stack: f72f0600 00000001 f6b16a2c f72f06a0 f72f0600 f8c6cb60 00000000 c0181dcd 
Dec 19 09:17:34 apollon kernel: [   32.004000]        f8c6cb78 f8c3b1f0 f8c3b230 f8c6cb60 fffefa49 f71af540 f71af540 f8c6cb60 
Dec 19 09:17:34 apollon kernel: [   32.004000]        dfe15800 f8c3be3d f71af540 f6b4fda0 00000001 f6b4fd1e f74eeaa8 f74eeaa0 
Dec 19 09:17:34 apollon kernel: [   32.004000] Call Trace:
Dec 19 09:17:34 apollon kernel: [   32.004000]  [sget+109/816] sget+0x6d/0x330
Dec 19 09:17:34 apollon kernel: [   32.004000]  [<f8c3b1f0>] nfs_set_super+0x0/0x40 [nfs]
Dec 19 09:17:34 apollon kernel: [   32.004000]  [<f8c3b230>] nfs_compare_super+0x0/0xe0 [nfs]
Dec 19 09:17:34 apollon kernel: [   32.004000]  [<f8c3be3d>] nfs4_get_sb+0x25d/0x370 [nfs]
Dec 19 09:17:34 apollon kernel: [   32.004000]  [vfs_kern_mount+182/304] vfs_kern_mount+0xb6/0x130
Dec 19 09:17:34 apollon kernel: [   32.004000]  [do_kern_mount+63/240] do_kern_mount+0x3f/0xf0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [do_mount+1643/1856] do_mount+0x66b/0x740
Dec 19 09:17:34 apollon kernel: [   32.004000]  [tcp_v4_send_check+68/240] tcp_v4_send_check+0x44/0xf0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [tcp_transmit_skb+1017/2048] tcp_transmit_skb+0x3f9/0x800
Dec 19 09:17:34 apollon kernel: [   32.004000]  [kunmap_atomic+94/160] kunmap_atomic+0x5e/0xa0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [kunmap_atomic+106/160] kunmap_atomic+0x6a/0xa0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [__handle_mm_fault+1671/2816] __handle_mm_fault+0x687/0xb00
Dec 19 09:17:34 apollon kernel: [   32.004000]  [__mod_timer+159/176] __mod_timer+0x9f/0xb0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [do_page_fault+905/1680] do_page_fault+0x389/0x690
Dec 19 09:17:34 apollon kernel: [   32.004000]  [error_code+114/128] error_code+0x72/0x80
Dec 19 09:17:34 apollon kernel: [   32.004000]  [copy_mount_options+171/336] copy_mount_options+0xab/0x150
Dec 19 09:17:34 apollon kernel: [   32.004000]  [sys_mount+119/192] sys_mount+0x77/0xc0
Dec 19 09:17:34 apollon kernel: [   32.004000]  [sysenter_past_esp+107/169] sysenter_past_esp+0x6b/0xa9
Dec 19 09:17:34 apollon kernel: [   32.004000]  =======================
Dec 19 09:17:34 apollon kernel: [   32.004000] Code: 74 24 10 89 6c 24 18 89 04 24 8b 2a 8b 52 04 8b 98 64 01 00 00 fc 89 54 24 08 8b 45 00 89 44 24 04 8b 33 89 c7 83 c7 10 83 c6 10 <f3> a6 74 16 31 c0 8b 5c 24 0c 8b 74 24 10 8b 7c 24 14 8b 6c 24 
Dec 19 09:17:34 apollon kernel: [   32.004000] EIP: [<f8c3b26c>] nfs_compare_super+0x3c/0xe0 [nfs] SS:ESP 0068:f6b4fcb4