Microsoft Access database problem

We have got an image database on our file server with a .mdb extension. When I try to open the file, Access starts but I get an error message. It says something like it needs to be repaired or it’s not a MS Access database file. First, I created a copy of the file, then I ran the repair utility. After it was done and I tried to open it again, Access just told that it was not an Access database. Help!