Class not registered (exception from hresult: 0x80040154 Err

Dear Team,

i am facing very critical problem getting error:-

Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))

Actually i am reading data from OPC server with Interop.OPCAutomation.dll(OPCDAAuto.dll) in VS2008 Express edition.Earlier it is giving Error of x86 because the reading window application is running in window7 64 bit OS but after changing target platform to x86 it will removed and working fine.

But suddenenly after some time this error come and i am not able to connect OPC server.

even in from Googly i did register successfully OPCDAAuto.dll with regsvr32 .

But even after this error persist.

Kindly Help me to resolve this problem urgently

Thanks in advance