We have seen instances where entire Windows Settings Groups (WSGs) are missing from a session, when they existed fine during the previous session.
Another issue has been that files in WSGs become corrupted or contain NULL characters after logon. For example this can happen with Outlook signatures which are captured in the 'Mail Profile and Signatures' WSG.
This has been observed to occur in the following scenarios:
- You have Local Cache mode enabled
- You have 'On Session Lock' or 'On Session Disconnect' enabled in the Windows Personalization Sync Options
- A user locks, hibernates or suspends their machine, or the machine is powered off or crashes (BSOD) while the data in the Windows Settings Group is being synced up to the server
- When the user logs back on they find files are corrupted, or that entire sets of WSGs are missing
Update - This issue has now been recreated and is covered in the Known Issue article: File synced by Windows Setting Groups has its contents replaced by Null characters
Currently there is no solution to this issue - basically a sync needs to be allowed to complete before the machine is shut down. During the sync lots of file operations are carried out and the OS can cause corruption if interrupted, or WSGs can simply fail to sync if shutdown does not occur cleanly.
You can work around it by disabling the 'On Session Lock' or 'On Session Disconnect' options, and encouraging your users not to power down their machine at the wrong time.