One thing you can do is use the SysInternals utility PsGetSID (http://technet.microsoft.com/en-us/sysinternals/bb897417.aspx). This won't solve the issue, but it takes KiXtart out of the equation.

The error happens when KiXtart tries to resolve SIDs, so I expect if you try to resolve the SID of a group on your logonserver with PsGetSID, the same error will occur.

Ruud