If you're saying you've reinstalled, then that basically rules out anything being off with your installation but it can't hurt to verify your cache (right-click CK2 in the Library > Properties > Verify Integrity of Game Cache). Only other two things it can be is something to do with mods (remember there's a scroll bar; maybe you've forgotten about one mod at the bottom of the list in the Mod tab) or beta patches (look under Properties > Betas). If nothing else works, reinstall again and make sure its truly a clean install this time by making sure there's nothing left.