Maybe your domain is static or dynamic? Maybe it keeps changing every night. (it happens to my professor in my University lectures... we're supposed to connect to a server but it's always a different IP).
I won't lie I don't know how to fix it. I can just give suggestions.
Hi there. In my office every user have a username/password to log in on a computer and use it. However rescently on my computer the following issue appeared - I cannot log in. Noone can. It sais that "Windows cannot connect to the domain, either because the domain controller is down or otherwise unavailable, or because your computer account was not found". So the thing I do to be able to log in is - I pull out the network cable, I restart the PC, I write my UN/PW without being connected to the domain controller and after that I plug in the network cable again. After that everything works perfectly. Is there anything I can do to easily fix this and I don't have to get through this every day?