Sometimes Second Life can corrupt your scripts so that things actually act weird. Oftentimes, you can fix that by a Smart Reset).

If that doesn't work, it means SL has borked it quite badly. Best to start over and get a fresh set.

You can get a fresh set by performing an update at the Update Switch. You can avoid re-setting up your gear by choosing "HUD only" and transferring all your gear over. More info here.

If you chose "new box", you need to re-setup. In which case, remember to activate any plugins you have after performing a re-setup or a fresh setup (you can't simply transfer arm cuff or thigh cuff plugins over, for example - you need to activate them on your new HUD).