Comp Freezes after installing SP2

I have a Median Laptop, and have had this problem for AGES now….

after installing SP2 on xp home. it will freeze, sometimes moving the cursor is enough to snap it back, other times i have to unplug it from the mains and it kicks back into life, the CPU temp is around 45-57 degrees, and i cant think of why it would do this. to get SP2 i have updated from a version of windows before SP2, so windows update goes through all the updates before SP2 was released.
… any help?