suffers

Last night my computer runs well without any problem. But the next morning it suffers a problem which I state in the title. I check the brightness and contrast settings,but nothing happens.

guylots of things heard from u about cabinets and power supplys, currently i m using a techcom basic(read suck) enclosure with as frontec 230 w power supply, the system suffers as it get hot, i m using pIV 2.4 prescott with 845gv chipset, my budget is 2K 8)