Cannot open apps because of a problem
I'm running OS X 10.7.5 (Lion) on a Mid 2011 iMac. I have recently found that Apps such as Preview, Quicktime, iPhoto and Adobe Photoshop will not open and I get the message 'Cannot open 'xyz' because of a problem'. If I then Restart the iMac everything is fine, everything opens as expected but then if I leave it overnight Apps start failing to load again so I have to repeat the cycle. Historically, I cannot restore the system from Time Machine because when the backup became full it failed to wrap around so I no longer have a backup. Does anyone have any ideas?
Earlier Mac models