HELP!!!

I've written a script which used IF INGROUP to assign drive mappings - it is working for most people, however some users are getting a system registry error and the following even is logged on the local machine

"The description for Event ID ( 2221 ) in Source ( KIXTART ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. The following information is part of the event: UserGetInfo failed Error : The user name could not be found. (0x8ad/2221)."

and

"The description for Event ID ( 1332 ) in Source ( KIXTART ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. The following information is part of the event: GetPrimaryGroup failed Error : No mapping between account names and security IDs was done. (0x534/1332)."

Please note there are two other associated events too - but they basically say the same thing....

I have checked the user is a member of the group - that the group name is valid - and that they have relogged in since adding them to the group - any ideas? The funny thing is, the drives still map properly, but I would like to eliminate the errors in event viewer if possible. Any help would be tremendously appreciated.

Thanks
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'I have often regretted my speech, never my silence.' Xenocrates (396-314 BC) Chris Jorgan