This is a pretty random issue we came across at my job but apparently this can happy with Windows 7. Users were randomly losing connection to their network share. It would tell them that the location is unavailable. We realized that the Offline files service in Windows 7 was running and for some reason it was causing their drive to go offline.
There is a simple solution for this. First, turn off and disable the ‘Offline Files’ service if you don’t plan on using it. Also, add the following registry key:
Create Key Name: FormatDatabase
Note: You don’t need to disable the service but there is no reason it should be running for desktop computers.
Warning: All cache files are deleted and unsynchronized data is lost. (applies to laptops that sync)