Is there a way to force PS back to defaults - settings, tool bars, etc ?
Otherwise, i would consider uninstalling PS and other programs, reboot, reboot again. And then reinstall and test one at a time.
If you make a full disk image snapshot you should be able to revert to that image version if you find an issue.
It well could be a memory leak or PS refusing to release memory with each image being opened until it runs out of working memory.
That used to be a known issue, but i thought it had been fixed a while back.