Hi dionan and Welcome to The Forum.
When "all of a sudden" this started, had you recently installed/uninstalled anything? If so you may be lucky and it created a Restore Point before doing anything, if so try the Restore Point first.
If not, type in a command prompt or the Run... window: sfc /scannow This will repair any corrupted system files it locates.
Definitely sounds as though your user profile has been corrupted, so at the end of the day you may need to create a new user profile and transfer all your files/folders over.