Exchange 2007 SP1 I seem to be getting this error quite a lot on my Client Access server. Done a vast array of searches but can't find anyone else with this error. Certainly is a vague one. Is there perhaps anything I do to increase logging for this error to find the route cause? Event Type: Error Event Source: MSExchange Common Event Category: General Event ID: 4999 Date: 26/11/2010 Time: 09:36:12 User: N/A Computer: CAS01 Description: Watson report about to be sent to dw20.exe for process id: 8088, with parameters: E12IIS, c-RTL-AMD64, 08.01.0240.006, OWA, mscorlib, S.I.Path.CheckInvalidPathChars, System.ArgumentException, 7ee, 02.00.50727.3615. ErrorReportingEnabled: False For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.