IanPritchett
Any ideas what might be causing this?
Not a clue, but a few suggestions...
1.) Check your Windows logs for any error messages -- particularly disk errors
2.) Try disabling virtual memory (swap file) temporarily. If you have a decent amount of RAM, this shouldn't be a problem.
EDIT 3.) Your hard drive manufacturer should have a downloadable utility on its website that checks the health of your drive. I would run that too.