Photoshop workspace problem. Application windows locked

Hi,

This is my first time posting,(forgive my wrong choice of technical terms too), I am operating off of an older version of Photoshop (CS5.1) on a Mac. It has worked well up until recently. When opening up a workspace window, the window fills up the application field, its in standard screen mode but I can't minimize it and it stays at the same size locked. Opening up another file brings it into the same workspace, I am able to pull it out of that workspace and bring down the image size but the background file still fills up the screen. Closing the background file will then cause the other file to lock as well. It makes trying to work  a real chore. Any ideas of how I can deal with this is appreciated.

Thanks