Ok, you asked .. here is the full story
Some time ago (1 year) I started to experience a very weird behavior from the system, that is, whenever I boot on Windows I can't click on Start menu button and some other graphic elements on the screen, as if there is a transparent graphic layer above almost all graphic elements, but I can use the keyboard with no problem (opening start menu, etc).
To solve the issue, all I have to do (in Windows) is to log off and then log back in, after that everything comes back to normal and pointer device can access all graphic elements.
To narrow down any driver/OS/virus (software) problem, I've unplugged the HDD and booted on Live CDs and Windows Setup CDs to test if the problem persists, and the same thing happens. It doesn't matter what it is, WinXP, Win7, Linux, RecoveryCD, all have the same issue with the pointer device. To make it work, I have to do some other tricky things (opening menus, etc) since Log off is no longer an option on a Live CD.
Next I went for the hardware, and I've tried a different video card (the current one is on PCI-E and the tested one was on PCI) and nothing changed. I've measured and tested different PSU, I've used different RAM modules, even the mobo was recently changed (because the old one was slowly dieing-> random POST fail until one day it completely refuse to POST; I suspect the BIOS flash) and nothing changed.
The only component that I didn't test yet is the CPU (couldn't find a spare AM2 CPU). So the only suspects remaining are:
1.CPU with faulty functions related to GPU, that does not affect the rest of functionalities, and some how get fixed when certain stuff are reloaded in RAM (log off, log on)
2.a very clever BIOS virus that slowly over a year damaged the BIOS flash(during this time I had numerous POST fail with a beep code indicating missing/broken video card, no matter what video card I used), kept a copy in MBR of the disk and now injected itself in the new mobo .. oh, the new mobo does NOT have POST fails.
Isn't this science fiction or what?
Oh .. and one more think, if I do a hard reboot with power cut off, the issue disappears, but if I don't cut off the power between reboots, issue persists
