I have had problems with usb devices in the past that prevent the system from booting. In my case, it was a hardware issue, because it affected both windows & Linux. You might try unplugging usb devices you have hooked up that you don't need. Another other external devices you don't need as well.
On my laptop, with the kernel I used to have, an SD card plugged in the external slot would cause a problem with interrupts. It was an mmc device, not a usb device. Subsequent updates have fixed the problem. In your case, you may not have the problem if you install Ubuntu 8.10.
If your computer is 64 bit, you may find the "nolapic" option will allow you to proceed with the installation.
ACPI is used for assigning interrupts, needed for power management, and some services such as hal & udev.