Is the machine a self build?
If so there could be a blockage in the information pipeline (Explanation follows)
Imagine your computer as a road system.
You are going along a motorway, then you go to a country lane before going back on a motorway.
When you hit the country lane, everything slows down(Narrow road), and then when you go back on the motorway the front traffic surges ahead, before the rest can catch up, causing a gap (freeze).
If the processor, graphics card, memory & bus lanes are not all running at the same speed, this is what happens.
Hope this helps