Sounds like maybe your profile is corrupt.
Instead of logging in at the sign on screen, use the power icon near the bottom while holding the shift key on your keyboard to restart your computer. This method should allow you to reboot into safe mode.
Give that a try for a few minutes and report back any problems.
Afterwards just reboot normally and see if your sojourn into safe mode moved the needle.
IF not you may have to create another local user account as a member of the local administrators group and see if that seems to work properly.
IF so then just move any critical data from the corrupt account over to the new account, into the proper, respective folder locations.