# What to do if the installation of the TAP-Win32 driver fails?

If your TAP-Win32 driver installation fails with a message such as "The system cannot find the file specified", it's possible that your registry is missing the all-important **RunOnce** Key. Windows 2000/XP has a bug that it cannot properly detect new hardware by *.inf files, if the "!RunOnce" registry key is missing. See [this article](http://forums.techguy.org/windows-xp/235959-cannot-find-file-specified-during.html) for more information.

Also, make sure that your system is not configured to silently reject unsigned driver installation.

For more information on managing tap-windows drivers look [here](/Pages/Managing%20TAP-Windows%20drivers).