I've having trouble reconciling "always locks up within 4 minutes of
cold power up" and "no problem if keep PC switch on permanently."
Perhaps you can elaborate on the second statement, as it seems to
conflict with the first.
Prior to starting to use broadband on July 25th there was no lockup problem.
(The Realtek ethernet Gigabit controller had been BIOS disabled for over 2
years.)
From Day 1 of using broadband (i.e. ethernet controller enabled) the PC
locked up, in a quite variable way and in various situations (the most
surprising being during entry of the BIOS password, and the most bizarre when
the screen blanked out, and the only action was continual attempts to access
the (empty) floppy disk drive).
Suspicion naturally fell on the ethernet controller (BIOS chip), so I
disabled it; no lockups occurred.. SO - putting 2 and 2 together (making 5 in
this case...) I kept it disabled and added an Intel Gigabit ethernet PCI card.
For 2 days (powering down overnight) I had no lockups, but on the 3rd day I
had it in spades, resulting in my Linux kernel being corrupted. (Fortuitously I
had taken a complete disk image backup the evening before, so was soon back in
business!)
Because the lockups always occurred within 5 minutes of cold power up, I
assumed there was some kind of cold-start problem - the opposite of overheating.
So I left the m/c running WinXP when not in use (e.g. overnight), with all
other gear powered off (including router).
It has now been continusously running for 6 days, wuth no sign of lockup.
It having been suggested by a friend (and having powered the PC down
overnight) today I unplugged and replugged all the power connections in the PC
(apart from the big one plugged into the motherboard, which I simply could not
get out).
After powering up from cold it has been running normally (WinXP, Kubuntu,
Mandriva) - but then it did for 2 days after installing the ethernet PCI card!
The strange thing about the cold power-up lockups is that - on rebooting, the
system then runs perfectly - for days.
So I don't see how it can be an overheating or battery problem.
(The variable symptoms remind me of buffer overruns in the old days.)
PC details:
Intel Pentium 4.3Ghz with twin 120Gb Maxtor IDE drives
Intel 865PE chipset motherboard with dual-channel DDR
1 GB ultra fast DDR RAM
Radeon 9600 128Mb VGA/DVI-I/TV-out
Many thanks for various responses - much appreciated...