Blooz,
I use a standard setup, so nothing to change in AH.
Although I have cleaned out the dust and had a few trouble free evenings, I regret that it rebooted again last night. I had a few hours on-line before this happened. When it happens again I will check the CPU temp in the BIOS. By the time I remembered to do this last night, there was no problem there at all. I suspect the CPU temp will be fine as I don't overclock anything.
So far, the only consistant piece of information I have is that this only happens when I play Aces High! So I am pretty sure it is when my system is being pushed a little harder than usual - No other games played, I'm not that sad yet
. Also worth remembering I have been playing AH on this PC for a long time without any problems whatsoever. Having thought about it, it is extremely unlikely to be AH software. It could still be due to heat in the system and I will first set about making sure that is in the clear. After that my only guess is that it is some intermittent hardware problem that currently may be impossible to pinpoint as it is so infrequent.
Once I have eliminated heat as probable cause I will probably go for a more extensive clean and even reset cards in their slots.
Edit:
The task bar icon flicker turned out to be the icon for my network connection and to be honest, I have not noticed it recently.