Tiki:
If you are running four 2 Gig RAM sticks you could try removing two of the sticks. Win will boot but not run super-well and you can see if things still freeze. If not, change to the other two sticks. That may show up a RAM problem. Some MBs will allow you to run with the memory sticks in any old slot, others require specific combinations. So depending on the MB, if the problem is not the memory stick, but a memory slot, you might not identify the problem if it happens to be a slot that you use only when four sticks are loaded.
Jack
If you are running four 2 Gig RAM sticks you could try removing two of the sticks. Win will boot but not run super-well and you can see if things still freeze. If not, change to the other two sticks. That may show up a RAM problem. Some MBs will allow you to run with the memory sticks in any old slot, others require specific combinations. So depending on the MB, if the problem is not the memory stick, but a memory slot, you might not identify the problem if it happens to be a slot that you use only when four sticks are loaded.
Jack