Missing DLL

I am the IT technician for a company that supplies wire harnesses to Daimler Crysler through JIT delivery. We are running an EDI (NT work station) server wich runs the communications between ourselves and DC. Every now and again, when I test connections to the printer, I get a missing DLL error. Even after I copy all the DLL’s back to the server, after a while I get teh same error. MS can;t seem to give me an answer. Can anyone else?