Can anyone figure out why I can't get PS Ext. CS6 to open?Could not initialize Photoshop because the

I have a mid-2011 Mini with 8 GB memory and a 1 TB 3rd party drive that I installed. It's the i7 processor, 2.7 GHz. All has been well for months now, until a week ago or so when I suddenly get these two messages upon trying to open PS: "Could not open a scratch file because the disk is not available," and "Could not open a scratch file because the disk is not available." I opened the machine yesterday to check the connector from the HD to the unit, put it back togther, and still no luck. PS is my main program! Been using it for almost 20 years now. Also, using Lion. Please help! Thanks! David.