Hi, I'm having this weird problem. Rarely, about every month or so, my graphics cards will do something very strange. For about a minute, they will go up and down between 0 and 95% usage. An audible buzzing sound occurs as well, but this sound doesn't occur in games even under full load. The event also occurs typically at around the same time as well, around midnight to 1AM (but I have no programs scheduled to scan/update anything during that time). The normal Windows 7 aero desktop reverts to the "basic" theme, with no transparencies, then reverts back after the event. System specs Core i7 920 3.8Ghz GTX 275 SLI (stock clocks) EVGA X58 Micro ATX 6GB DDR3 Memory 750W PSU Windows Home Premium Driver: Nvidia 197.13 Any help would be appreciated.