Galaxy S3 low memory problems (Unfortunately, system UI has stopped). topic

Hi, I was having problems with my S3 recently on CM 11 mod - chrome crashing, slow-to-appear keyboard etc when I got fed up with it, did a factory reset, and installed blisspop. But the problems persisted. Now I'm constantly getting the "Unfortunately, system UI has stopped" which I consider to be a problem of the same vein - memory leak or something that has got to be related with the memory. Is there any particular app that might be the problem or I'm looking at it from the wrong angle?

Thank you.