You may get into trouble if you didn’t remove folder synchronization on network server before deleting a user account or unlink a computer from domain… File synchronization still effective even if the user is no longer on the computer or Active Directory.
The only way to get rid of old entries, is to do it manually through the registry.
First, open up the registry editor (Start > Run) :
regedit
Go to :
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\NetCache\
Then, add a DWORD key named :
FormatDatabase
Reboot the computer and your done.