TimeOut error

We have developed a Visual Basic 6.0 program which uses Microsoft ActiveX Data Objects 2.5 & SQL Server 7.0. The program was running on Windows 2000 with SP3 for about one year. After installing Navision 3.1 on the workstation, the application gets an ODBC Timeout error. We have narrowed it down to installing Navision by setting up a new workstation and reproducing the problem. We have reinstalled MDAC 2.6 SP2 and also MDAC 2.7. Both have not solved the problem. We have also changed the Command Timeout in our program. We have tried 600 and 0. We would appreciate any assistance.

No ideas ?