Try opening MS Access and doing the repair.
1. Close the Network Performance Monitor.
2. Open Microsoft Access (2000 or later).
3. Select "Tools->Database Utilities->Compact and Repair Database"
4. Select the Network Performance Monitor database SWNetPerfMon.cfg file. This is located in your SolarWinds directory (C:\Program Files\SolarWinds\200X Engineers Edition or C:\Program Files\SolarWinds\Engineers Edition).
thanks, it worked