Windows 7 forum: Windows 7 Freezes after being Idle, or after Sleeping..

<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">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.
<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">I have tried system restore, Defragmentation, and virus checks. Running out of ideas!
<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">I'm using x64 Windows 7, and my specs are as follows.

<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">AMD Phenom II X4 955 Processor 3.20GHz
<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">4.00Gb Ram (2x2gb Sticlks)
<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">ATI Radeon HD5770

<span style="color: rgb(50, 50, 50); font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; background-color: rgb(246, 250, 251); ">Help please!