Path must be rooted Exception

Hi,

I keep seeing the following error in the event log:

Exception Type: System.ArgumentException
Message: Path must be rooted.
ParamName: NULL
TargetSite: System.String GetDirectory(System.String)
HelpLink: NULL
Source: System.Web

Exception handling is managed using the Microsoft Exception Application Block. "Path must be rooted" is not a custom error message that has been thrown so I'm a little confused! There seems to be no information on the net about this error either.

Anyone have any ideas?

Thanks
Paul.