The factory reset worked to fix the error - my sims were freezing every few seconds and time would freeze then jump forward a couple of sim hours. After the reset it loaded faster, ran smoother just the way it should run...
..the only problem is that even though I've transfered virtually all the folders from my backup, some of my towns dissapeared - dragon valley and midnight hollow etc although the saved games I had in those towns stayed but from the main menu I can't start a fresh game in the towns I've downloaded. Also in one of my dragon valley games the school and the statium dissapeared. Anyone know how to get these back or make sure they don't delete themselves? I doubt I missed an important folder I checked them off as I made the transfers. I also tried transferring the entire backup over in one hit but this just transferred the bug.