>we have an app that will run on the server but not over the network. it runs over a mapped network drive through the network. the file is on the server but we use the mapped drive to access it.

When I had a situation like this, it was related to the fact that we had to switch to UNC. I am not saying this would resolve the situation but it would something be to look for. I see William suggested it to you. I also see that you mentioned that your app needs to work with a map drive. When I had to resolve that issue, I build a UNCMapping class in my framework which I use to establish relationships between a map drive and its UNC equivalent.