Thanks a lot Martin!You are right, the RegAsm.exe was corrupted.
Before posting, please read how to report bug or request support effectively.
Bug reports without an attached log file are usually useless.
While registering WINSCP COM library , executing this command :
C:\Windows\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe WinSCPnet.dll /codebase /tlb
creates an error Microsoft.NET\Framework\v2.0.50727\RegAsm.exe is not a valid Win32 Application.
On running thte command regsvr32 WinSCPnet.dll creates the error DllRegisterServer entry point was not found.