Random Mini Freezes

[spacemonkey797]

Most of the time my game will freeze as I'm walking around and will unfreeze after a couple of seconds and then freeze again after taking another couple of steps. Causing me to take a minute or so to get across a couple of meters.

weird thing is that sometimes it work perfectly fine without any problems.

system specs:

AMD Athlon processor LE- 1640 (2.7 GHz)
3 gigs RAM
Windows Vista 64bit OS
Nvidia GeForce 9500 GT