Windows 8.1 randomly drops mapped network drives

MACHINES

File Server: Windows 2003 Server
Domain Controller: Windows 2003 Server
Client: Windows 8.1 Pro

PROBLEM

The client is not a part of the domain which the file server and obviously the domain controller are. The mapped drives are added on the client using DOMAIN\User (along with password).

Every morning when coming into the office, I have to reboot my machin ein order to get my mapped drives back. This is very annoying. The same issue when I log in remotely (using RDP) when working at night. I have to then reboot the machine in order to gain access to my mapped drives.
It seems at random, my mapped drives (residing on the file server) goes away. It has happened once while I was actively working on the client. But daily the above issue occurs.

I'm at a loss to what to try. Most issues I've seen are related to mapped drives disappears when the machine is rebooted, but my issue is reversed, so those fixes I've tried that has been suggested do not apply or work.



Any help in finding a solution to the very annoying problem is greatly welcomed.

Side Note: Windows XP and Windows 7 machine do not have this issue and they add the mapped drives in exactly the same way.

Who is in charge of the network?

I am