Odd issue with Latitdue D820 & BitLocker

We have a few D820's in our company, and 2 running Vista Enterprise.  These 2 D820's have BitLocker enabled, but what it has caused is locking these users account in AD 2-4 times per week.  We have engaged MS and they are not sure what the cause is, they are pointing back to hardware.  We have BitLocker on Vista running on numerous machines, and these are the only 2 that have this issue.  One of the users went to the Windows 7 RC client, and used BitLocker and the issue went away.  But he has since put on the RTM version and the issue just started up again.  We are very confused with this issue, and wondering if anyone else has seen this, or have any ideas.

Thanks