Offline File Synchronization – In Windows 7 the “Work Offline/Work Online” option button disappears from Windows Explorer after an offline / online transition and the Client Side Cache remains offline until the next restart of the computer
You have Windows 7 configured for offline file synchronization to synchronize content from network shares and have it available offline. Users notice that Windows 7 changes usually to offline mode; however Windows 7 does not switch back to online mode automatically after the network becomes available. Synchronization of the UNC path is not possible, and in the Sync Center no information is available for the offline file synchronization partnership.
If the user accesses network resources in Windows Explorer, some network resources are online and accessible; however when the user tries to access resources that have been made available offline, the offline content is displayed from the Client Side Cache. The user can create new files and change existing files, but these files remain in the local cache.
You provide a file share and subfolders for every user like in the following example:
A user with the appropriate permissions can access subfolders dir1 and dir2 but do not have permissions to view the content of the share ShareName$.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB2512089.