|You have 256 MB of RAM ???|
You should install more, over 512 total.
Most Virus and Spyware scans are likely to work better in Windows Safe-Mode. Safe-Mode uses a minimal
set of device drivers and services to
start Windows. And alot fewer Processes
running in the background.
Maybe your Harddrive is not running up to speed.
Harddrive manufacturers have software for download for testing HDD.