If your harddrive is full, or almost full... that will happen sometimes. Try deleting files not needed, burn files you rarely use to a CD/DVD, and defragment your drives/partitions. If that doesn't work, I'de reccomend re-installing your Windows/Preferred OS.
Intel Pentium 4 - 3.5GHz
3024mb DDR2 778MHz RAM
160gb SATA + 40gb IDE
nVidia GeForce 7600GT (750mhz Core /1200mhz RAM)
Apeva X-Discovery + Blu Orb II + Zalman VGA Cooler