I was troubleshooting an issue with the Claims to Windows Token Service the other day and found a great tool to assist. I was working in a SSRS integrated environment configured with Kerberos and was getting the error “Cannot convert claims to windows token” when configuring a data source to test against. The issue was that the C2WTS service account was not in the local admin group. I had requested this access, but in this environment the local admins were all in an Active Directory Group and I did not have permissions to confirm this and adding the account in local admin explicitly was whipped out with Group Policy. Anyways, enough about the issue..the awesome tool is at http://rodneyviana.codeplex.com/releases/view/19103 and is called c2WTS tester
Add it to your SP Admin tool belt!