There's not really a pattern; I would even say no pattern at all, it just happens, and that is what buggers me...I never dropped it, it worked flawless for way over a year and now it's starting making problems...

I tried the "Ctrl-T" test, and got nothing strange out of it...

I'm going to bed now as it's 2 in the morning here, but I'll check the mainboard for some partially disconnected components that may be due to a dry solder joint?

thanks for your help, paul; I really hope we can sort this out...