Robert,

In deed looks very strange.

Does your new SQL Server installation goes well without any problem? Have you created test DB and test?

If new installation is working fine:

As you mention it's having problem in finding MDF file; hence I suggest you to detach and attach the user as well as system DB. Hope should work fine.

Also from other computer start SQL Profiler to fetch any error which might give you more visibility.

Good Luck!!!

FM