Cool - though you could have done this by editing /boot/grub/menu.lst
What we've done, likely, is established that acpi is the problem.
Booting "noacpi" means that your fan will always run etc. Anything relying on power management will not work. For laptops, this can be pretty sucky but if you don't mind then that's as far as you need go.
If you want power management, then you'll have to supply, and/or repair, the DSDT table which linux reports as missing. The acpi project often has working dsdt for download. But this is pretty much advanced-end work. It is just sad that some vendors provide the things needed for acpi to work in a non-standard place (i.e. so only windows will work).
However - I often find that entering bios setup and disabling all the "advanced power" features does wonders. Often the advanced features in the bios are only needed to make up for deficiencies in windows. With your particular problem, there is often a power management option where you configure network devices. It may just be that bios put your nic to sleep when it was unused and the kernel could not turn it on.