Same problem on my Acer Ferrari 4005 since upgrading to Edgy , with a custom 2.6.18 kernel.

I've tried removing the ochi1394 as suggested by Ralf but that does not resolve the peoblem for me.  I still see frequent APIC errors, although they seem to be reduced (slightly) since removing the ohci module.

lsmod output is:

Module                  Size  Used by
binfmt_misc             9868  1 
rfcomm                 34608  0 
hidp                   13440  2 
l2cap                  19976  10 rfcomm,hidp
ipv6                  250464  10 
hci_usb                15708  2 
bluetooth              45796  8 rfcomm,hidp,l2cap,hci_usb
nfsd                  248936  13 
exportfs                4928  1 nfsd
lockd                  61648  2 nfsd
sunrpc                147656  8 nfsd,lockd
capability              4552  0 
commoncap               6336  1 capability
fglrx                 455540  8 
driverloader          296096  0 
powernow_k8            10584  0 
cpufreq_userspace       3924  0 
cpufreq_stats           5256  0 
freq_table              4040  2 powernow_k8,cpufreq_stats
cpufreq_powersave       1984  0 
cpufreq_ondemand        6064  1 
cpufreq_conservative     7108  0 
video                  16392  0 
sbs                    14456  0 
i2c_ec                  4928  1 sbs
dock                    5968  0 
button                  6240  0 
battery                 9288  0 
container               3904  0 
ac                      4616  0 
asus_acpi              16420  0 
af_packet              17612  4 
nls_iso8859_1           5504  1 
nls_cp437               7168  1 
vfat                   12032  1 
fat                    47280  1 vfat
dm_mod                 52464  0 
md_mod                 71452  0 
sr_mod                 14820  0 
sbp2                   22792  0 
scsi_mod              135664  2 sr_mod,sbp2
lp                     11080  0 
joydev                  9984  0 
pcmcia                 33624  0 
snd_atiixp_modem       13516  0 
snd_atiixp             17236  1 
snd_seq_dummy           3460  0 
snd_seq_oss            31616  0 
snd_seq_midi            7680  0 
snd_rawmidi            22272  1 snd_seq_midi
snd_seq_midi_event      7104  2 snd_seq_oss,snd_seq_midi
psmouse                39056  0 
serio_raw               6340  0 
snd_ac97_codec        103448  2 snd_atiixp_modem,snd_atiixp
snd_ac97_bus            2688  1 snd_ac97_codec
snd_pcm_oss            43392  0 
snd_mixer_oss          16384  1 snd_pcm_oss
parport_pc             34088  1 
parport                35468  2 lp,parport_pc
evdev                   9856  2 
yenta_socket           25100  1 
rsrc_nonstatic         10944  1 yenta_socket
pcmcia_core            36380  3 pcmcia,yenta_socket,rsrc_nonstatic
snd_pcm                76620  4 snd_atiixp_modem,snd_atiixp,snd_ac97_codec,snd_pcm_oss
pcspkr                  2944  0 
shpchp                 35624  0 
pci_hotplug            29804  1 shpchp
i2c_piix4               8908  0 
i2c_core               19032  2 i2c_ec,i2c_piix4
snd_seq                50400  6 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_timer              20424  2 snd_pcm,snd_seq
snd_seq_device          7508  5 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq
irda                  189868  0 
crc_ccitt               2240  1 irda
snd                    54248  13 snd_atiixp_modem,snd_atiixp,snd_seq_oss,snd_rawmidi,snd_ac97_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_seq,snd_timer,snd_seq_device
soundcore               8480  1 snd
snd_page_alloc          8336  3 snd_atiixp_modem,snd_atiixp,snd_pcm
ext3                  119568  1 
jbd                    51248  1 ext3
mbcache                 7688  1 ext3
ieee1394              349304  1 sbp2
ehci_hcd               30024  0 
ohci_hcd               18692  0 
usbcore               124712  5 hci_usb,driverloader,ehci_hcd,ohci_hcd
ide_generic             1408  0 [permanent]
ide_cd                 38944  0 
cdrom                  36712  2 sr_mod,ide_cd
ide_disk               14080  4 
generic                 6276  0 [permanent]
atiixp                  5392  0 [permanent]
thermal                13264  0 
processor              22524  2 powernow_k8,thermal
fan                     4360  0 
vga16fb                11992  0 
cfbcopyarea             3968  1 vga16fb
vgastate                8256  1 vga16fb
cfbimgblt               2944  1 vga16fb
cfbfillrect             4416  1 vga16fb