Problem with hibernating PC and 6.06

[Bernard Peek]

I've been using an old PC as a file-server and Samba domain-controller.
After replacing 5.10 with 6.06 I have a problem. If the PC is left it seems
to go into hibernation. It's difficult to tell because the display is blank
and the machine doesn't respond to the keyboard or mouse. I've disabled all
of the power options I can find in both the BIOS and in the Ubuntu
administration options, but it still happens.

I have a temporary workaround, I have another box pinging the Ubuntu machine
every 60 seconds. That seems to keep it awake.

The hardware is an HP Vectra VL with a PIII/500 and 128Mb RAM.

Any ideas?