If Safe Boot works, and indeed a second account works, then some login item on the main account is blocking other programs from loading. So, you'll want to log in to this account via Safe Boot, then disable all the login items. Then you enable them one by one, rebooting in between (or at least logging out and back in, but you need to reboot at least one time to get out of Safe Boot) until you find the one that is causing you problems.