Weird behaviour after drivers installation
 

Hello, a while ago I was in need to change some drivers (network and graphics). Unfortunately one problem appeared which I'm unable to solve. Once a few days (3-5) my computer seems to "freeze", the screen just goes blank, caps and scroll leds keep blinking. I'm quite sure this must have to do something with recently installed network or graphics drivers.
However, I don't know where to find any information about this error. syslog is empty and after a reboot everything works ok. Does anyone know where to find some info about what's wrong? I'd like to find this out instead of trying/replacing new drivers.

Thanks in advance,
Michael.