DLL Not Found

I've made a dll that I use to do fast wordsearches in files. I was using this dll in a APS.NET webapplication just until now, when the server suddenly doesn't seen to find the dll at "path\webAppName\bin\fs.dll". The path is correct and the dll are there, is isn't 0 k big, and I've tried to replace it with a backup. I've also restarted IIS, and tried tampering with the permissions, nothing seems to work

I run the application at IIS 6.0 at a Windows 2003 Server.

Here's the errorcode:

Exception Details: System.DllNotFoundException: Unable to load DLL (C:\Inetpub\wwwroot\GU9900\bin\fs.dll).

Very,very thankfull if someone can help me out!