Thanks for the additional information: some other things I'm wondering is what you were doing with the system and what applications were running when you get these errors.

Look at this as a process of elimination. checkdisk "surface scan" do not automatically fix errors. This is a full drive surface scan, to check the integrity of your hard drive, so that it's reporting the correct size, capacity, and that all sectors are able to be written too error free etc.. If it turns up any errors, make note of any errors and post them here.

If the disk scan turns up OK no erros, no bad sectors, perhaps your application is using up alot of system resources, and physical ram page sectors that windows needs to run are getting over-written by the application... IF your application/s are NOT being used when this error occurs, it could be faulty memory, or some such thing. Let me know if any of this is helping.

Can you download and install/run hijackthis? post me up your log, but don't fix anything, thanks.