DISM .exe /Online /Cleanup-image /Restorehealth
sfc /scanow
net use * /d
If you're running dism and sfc, you would have needed to launch cmd.exe with "run as administrator". That elevated cmd.exe will not see drives mapped from non-elevated processes unless you added the registry key for EnableLinkedConnections.
http://woshub.com/how-to-access-mapped-network-drives-from-the-elevated-apps/
Try running cmd.exe without "run as administrator" and then try "net use * /delete".
When you access the server, do you always initiate the session the same way? That is, do you always map a drive letter, either from a "net use" command or the Explorer? Does "net use" show that drive before you try to map a drive with the second account?
What about granting access to your desktop login account to access all file shares so that you don't need to use a second account?