ronin, this might identify a problem with the hard drive itself, which is what I'm suspecting. I'm on Win 7, so if you have XP or Vista things may vary a bit.
Method 1
CTRL-ALT-DEL
Select Task Manager
Select Performance (it will likely just show CPU and Memory, so next step is required)
Click Monitor Resources button (you should now see graphs of HD read performance)
Does the HD look normal, which is spiking up and down, or is it flat out at the top?
Method 2
While still in Task Manager
Click the Process Tab
Click the CPU column header, which will arrange by most used.
"is anything hogging the CPU??" If so that is the culprit and needs Uninstall/Re-Install
Method 3
Click Start
Click Control Panel
Select Classic View (if not already in it)
Double-Click Administrative Tools
Select Event Viewer
Does it show lots of errors, or other messages that give a clue to what you see happening?
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