This suddenly began occurring about a week ago. The system runs fine, however if it is left for a fairly short period of time (15-20 mins) The program am I using will freeze and the cursor will change to loading. The task bar will then freeze if I try and click 'start', and I have to hold down my Power button to turn the PC off. I have tried system restore, Defragmentation, and virus checks. Running out of ideas! I'm using x64 Windows 7, and my specs are as follows. AMD Phenom II X4 955 Processor 3.20GHz 4.00Gb Ram (2x2gb Sticlks) ATI Radeon HD5770 Help please!