Unkown Error

[Anon]

When I try to view a php file I get the following error:
Fatal error: Unable to open c:\inetpub\wwwroot\board\login.php in Unknown on line 0

It also happens with any other php files, and it started from nowhere. Yesterday everything was fine, and I'm the only user on this computer. I'm running windows 2000 with IIS 5 and PHP 4. Please Help.
Thanks,

[Anon]

Do you have include or require anywhere? Moved or deleted any files since the last time it worked?

If that's not the issue, show the code because I remember having the same problem and I fixed it quickly but I can't quite remember what that was actually ;-))