I found the problem on my Acer Extensa 5635Z (details above) just turned off acpi in /boot/grub/menu.lst
## ## End Default Options ##
title Ubuntu 9.04, kernel 2.6.28-15-generic uuid 5e06e3a7-6489-4e7d-bbbd-2ddf8cff1d69 kernel /boot/vmlinuz-2.6.28-15-generic root=UUID=5e06e3a7-6489-4e7d-bbbd-2ddf8cff1d69 acpi=off ro quiet splash initrd /boot/initrd.img-2.6.28-15-generic quiet
title Ubuntu 9.04, memtest86+ uuid 5e06e3a7-6489-4e7d-bbbd-2ddf8cff1d69 kernel /boot/memtest86+.bin acpi=off quiet
### END DEBIAN AUTOMAGIC KERNELS LIST
I found the problem on my Acer Extensa 5635Z (details above)
just turned off acpi in /boot/grub/menu.lst
## ## End Default Options ##
title Ubuntu 9.04, kernel 2.6.28-15-generic 6489-4e7d- bbbd-2ddf8cff1d 69 2.6.28- 15-generic root=UUID= 5e06e3a7- 6489-4e7d- bbbd-2ddf8cff1d 69 acpi=off ro quiet splash img-2.6. 28-15-generic
uuid 5e06e3a7-
kernel /boot/vmlinuz-
initrd /boot/initrd.
quiet
title Ubuntu 9.04, memtest86+ 6489-4e7d- bbbd-2ddf8cff1d 69 +.bin acpi=off
uuid 5e06e3a7-
kernel /boot/memtest86
quiet
### END DEBIAN AUTOMAGIC KERNELS LIST