Help!!! I have started having problems with scrolling using Firefox/windows 7, google Chrome works OK, any suggestions?

Hi, watched a couple of guys mucking around on there Trials Bikes the other day and as i used to ride motorbike Trials in younger days, I thought it might be fun to get a trials Bicycle, These days I ride a SS 29er,
What would be a good starter bike for a 46yr old 6'2" 120kg rider, Please dont fall ...