Do you really mean Domain user (logs onto a domain server) or just a user (account on the computer)
If you do mean domain user... when logging in to a domain as soon as the credntials are verfied a bunch of settings are sent to the computer called policies. I am sure that one of these policies s causing the restart and you will need to scrutenise them from the server removing anything suspicous. It is also possible that this is due to the motherboard change and an easier fix may be to create a new user account on the server.
If you mean local user, just backup your data with dmailer backup here: www.dmailer-backup-software.com from the administartor account and reinstall windows. You do not need to format when you are asked to just select leave current OS in tact however it is a good idea to format and start fresh every few years.(kinda like an oil change)
