ODBC Installation error

I am trying to install an ODBC driver for Informix on an NT workstation. I have done this several times before on other workstations, and had much better success. It seems something has a hold over the file <msvcrt.dll>, therefore the installation process is unable to write to this file. Does anyone know of a way to tell which application is locking this file? I have nothing running, I checked the task menu. I disabled all appls in the services that I felt may be the culprit, but still get the same error "file is locked by windows". any help would be greatly appreciated. Tks, Lo