Photoshop can use a lot of memory both physical and temp as per the swap file. it also uses it own cache system using scratch disks and any of these could be causing the problem. It's also possible that Windows isn't clearing the cache from system memory, which is then partly overwritten by another process or there is a overflow memory problem. All these could result in the problems you reported.
You need to look in Event Viewer and find tthe error message to give you a clue as to what is causing the problem.