Personally I think its the folder settings. Win NT allows you to do that thumbnail thing to all of your folders and if you change it back to details the Pboost problum goes away. I have this problum at work when i use adobe photoshop, it doesnt let me save my work if i went any were near a folder and viewed it as a thumbnail untill i reset the folder to details. Its gives the same error about the file being in use by another program.