Shortcuts not working

I’ve been using version 4.3 on Windows 10. When I first installed Krita everything was fine and then after a while shortcuts like ctrl+z and E (erase) just weren’t working. I tried resetting the configurations, closing and opening the app and nothing seemed to do the job. After a few minutes, sometimes hours the shortcuts worked again but when it took too long the only quick solution was to reinstall, but then it just happened again.
Does anyone else have this problem? what could be wrong?