SQL Server 2000 error and .NET error deciphering

Hey all,

I have an application that gives the following error upon login:

System.InvalidCastException: Cast from type ‘Guid’ to type
‘String’ is not valid.

Without going into detail about the application, can someone give me a generic meaning of this error message? It appears that as long as SQL Server 2000 replication is turned off there is no issue. Any and all help would be greatly appreciated.

Thanks in advance
Always
Alex Wildes
MCITP:SQL SERVER 2005 DBA