Fatal Error in Quartus

Getting following error, when running I/O assignment analysis.

*** Fatal Error: Access Violation at 0X78050C90

Module: quartus_map.exe

Lock in use: 4

Stack Trace:

0x50c8f: DGAPI_GetPlugInContext + 0xc81f (DgApi)

End-trace

This happens after moving from 9.x to 10.0. Issue persists in 10.0, 10.0 rev2 and 10.0 SP1.

Can some one help me out