Following on with some PMs with Adam, looks like my touch screen may have been the culprit. I am using a samsung DP700 Series AIO PC.
I don't use touch screen (keyboard is closer than screen) and didn't have drivers installed, but Win7 still had it activated.
Unticked check box as per graphic and have been merrily clicking away without crashing.
Off to gym, will get stuck in to new site after that and report back.
hopefully this will be of help to one or 2 others having problems.
Cheers
david