i know i say this a lot, but one thing you can try before any "re-install" is to toss your PREF file. The preference file hold a lot of info while you play around in Photoshop and sometimes it get corrupted. 

 

whenever PS gets wonky on me, nine-outta-ten times, it clears up after getting rid of the PREF file. (PS will rebuild it next time it launches...) 

 

hope it helps,

:)
retrocity