I have been having this error in SharePoint show up often:
An unhandled exception occurred and the process was terminated.
Application ID: /LM/W3SVC/1640420947/ROOT
Process ID: 5788
Exception: System.Security.Cryptography.CryptographicException Message: Keyset does not exist
at System.Security.Cryptography.CryptographicException.ThrowCryptogaphicException(Int32 hr) at System.Security.Cryptography.SafeProvHandle._FreeCSP(IntPtr pProvCtx) at System.Security.Cryptography.SafeProvHandle.ReleaseHandle() at System.Runtime.InteropServices.SafeHandle.InternalFinalize() at System.Runtime.InteropServices.SafeHandle.Dispose(Boolean disposing) at System.Runtime.InteropServices.SafeHandle.Finalize()
I found this description of the issue:
However, that mentions that this error is occuring in 'OWSTIMER.EXE', where as in my process it is happening in 'w3wp.exe'. Would this mean that this is happening outside the SharePoint Timer services?
It happens enough to cause the 'Rapid Fail Protection' in IIS to trip and shutdown the app pool.