This issue can be attributed to a lot of different issues, probably not a bug/virus but password cache issue or something similar. Sometimes a reboot of all the devices on your network will fix this. I would certainly delete all the existing network connections, reboot, and then re-establish them.
There are several good posts on this issue if you do a search. Here’s some links you may want to read:
Fifewarrior: Invalid User Name or Password Error - Fix
mike27oct: How to resolve Network shares access problems
Good Luck
-P
