Do files you download disappear before you ever get a chance to open them? This can happen in Internet Explorer 6, 7, and 8 as well as all versions of Firefox.
Downloads keep Disappearing?
Usually it is the result of an improperly installed Anti-virus program. Often it is AVG that was not entirely uninstalled. What happens is whenever the browser downloads a file once it is finished it runs the systems Anti-virus program to scan the file. If the program is not working properly the browser fails to run it and thinks something screwy is going on so it deletes the file.
Clean up Anti-Virus programs
Usually this can be fix by running the clean up tool for your anti virus product. For AVG 8 or 9 run AVG Remover . For Norton run the Norton Removal tool . For McAfee run McAfee Consumer Products Removal tool. Once the clean up is done your downloads should work fine. If not keep reading.
How to disable virus scanning of downloads in Firefox
Usually this is only necessary if FireFox stalls at “Scanning for Viruses.” Go to about:config then search for “scanWhenDone“. Click on it so it says false. Your downloads should now work fine.
Unfortunately there really is no way to disable scanning for IE so you might have to reinstall windows if things are really screwed up.