I just updated with the kernel from the PPA from Kamal and we are back to normal. Thanks a lot.
However, there is something else. One out of 3 or 4 times, when I turn the computer on I get this weird error.

1. When booting up, the kernel ring buffer is printed out on the screen. This usually does not happen. (When it does, I know I will have to restart ubuntu again).
2. The fan starts going crazy, it speeds up in several stages until maximum speed is reached (and remains like that).
3. I cannot adjust the brightness. I have to restart (sometimes twice) to get a normal session.

The funny thing is that it is not always like that. I had a look at dmesg and I got the following excerpt from it:

[    1.935348] ------------[ cut here ]------------
[    1.935410] kernel BUG at /build/buildd/linux-2.6.35/kernel/workqueue.c:312!
[    1.935520] invalid opcode: 0000 [#1] SMP 
[    1.935637] last sysfs file: /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/bcdDevice
[    1.935684] CPU 0 
[    1.935714] Modules linked in: ahci libahci atl1c
[    1.935870] 
[    1.935900] Pid: 36, comm: kacpi_notify Not tainted 2.6.35-24-generic #40+kamal~mjgbacklight1-Ubuntu LL1                             /Lenovo IdeaPad Z
[    1.935963] RIP: 0010:[<ffffffff8107af19>]  [<ffffffff8107af19>] queue_work_on+0x49/0x60
[    1.936042] RSP: 0018:ffff880152ec5d50  EFLAGS: 00010286
[    1.936081] RAX: ffff880150b62c90 RBX: ffff880150b62c00 RCX: 0000000000000000
[    1.936126] RDX: ffff880150b62c88 RSI: ffff88015350b1c0 RDI: 0000000000000000
[    1.936170] RBP: ffff880152ec5d50 R08: 0000000000000000 R09: 0000000000000000
[    1.936214] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000080
[    1.936258] R13: ffff88014f854000 R14: ffff880152564800 R15: ffff880152ec5fd8
[    1.936303] FS:  0000000000000000(0000) GS:ffff880001e00000(0000) knlGS:0000000000000000
[    1.936350] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[    1.936390] CR2: 00007f57c3a08560 CR3: 0000000001a2a000 CR4: 00000000000006f0
[    1.936436] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    1.936479] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[    1.936524] Process kacpi_notify (pid: 36, threadinfo ffff880152ec4000, task ffff880152eb16e0)
[    1.936611] Stack:
[    1.936660]  ffff880152ec5d60 ffffffff8107af6f ffff880152ec5d70 ffffffff8107af98
[    1.936798] <0> ffff880152ec5d80 ffffffff814402e2 ffff880152ec5db0 ffffffff81339490
[    1.937002] <0> ffff880150794c80 ffff880151879798 ffffffff8130a8c5 ffff880001e19000
[    1.937251] Call Trace:
[    1.937305]  [<ffffffff8107af6f>] queue_work+0x1f/0x30
[    1.937364]  [<ffffffff8107af98>] schedule_work+0x18/0x20
[    1.937426]  [<ffffffff814402e2>] power_supply_changed+0x12/0x20
[    1.937488]  [<ffffffff81339490>] acpi_battery_notify+0x9d/0xa6
[    1.937551]  [<ffffffff8130a8c5>] ? acpi_os_execute_deferred+0x0/0x36
[    1.937614]  [<ffffffff8130da85>] acpi_device_notify+0x19/0x1b
[    1.937676]  [<ffffffff8131b955>] acpi_ev_notify_dispatch+0x67/0x7e
[    1.937740]  [<ffffffff8130a8ee>] acpi_os_execute_deferred+0x29/0x36
[    1.937802]  [<ffffffff8107a775>] run_workqueue+0xc5/0x1a0
[    1.937864]  [<ffffffff8107a8f3>] worker_thread+0xa3/0x110
[    1.937924]  [<ffffffff8107f620>] ? autoremove_wake_function+0x0/0x40
[    1.937986]  [<ffffffff8107a850>] ? worker_thread+0x0/0x110
[    1.938047]  [<ffffffff8107f0c6>] kthread+0x96/0xa0
[    1.938107]  [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10
[    1.938168]  [<ffffffff8107f030>] ? kthread+0x0/0xa0
[    1.938227]  [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10
[    1.938286] Code: 75 29 44 8b 46 20 45 85 c0 75 24 48 63 ff 48 8b 06 48 89 d6 48 03 04 fd a0 f2 ac 81 48 89 c7 e8 1e ff ff ff b8 01 00 00 00 c9 c3 <0f> 0b eb fe 8b 3d c5 4a a5 00 eb d4 eb 09 90 90 90 90 90 90 90 
[    1.939990] RIP  [<ffffffff8107af19>] queue_work_on+0x49/0x60
[    1.940075]  RSP <ffff880152ec5d50>
[    1.940176] ---[ end trace b7caf1fb48b24338 ]---

Any suggestions? Thanks in advance.

Omar