I have used SugarCRM on and off for a couple of years, and boy it would crash on just about anything I did. I just
came across SuiteCRM a couple of weeks ago and they are very stable. I have installed about 7 modules so far
with no probems. I had the same problem on what you needed. Try this link out, it night help it installed with no problems:
I think you would have add your own JavaScript to validate something like a National Insurance etc. This is not hard to if you are a programmer. My blog has information on how to add your own JavaScript to an editview.