So I got my new G2 a couple of months ago and haven’t put it down that much since. Well, last night I installed *something* (game/app) that stopped the accelerometer working. I was close to tears. Not really. But I was bloody irritated and it took a while to find out how to kick-start it again. Whilst Les watched Moulin Rouge (again), I browser forums and played. Finally found the answer in a really obscure place (OK combination of places) – the HTC website and the androidforums). Answer: factory reset. Nothing else required.
http://androidforums.com/htc-magic/5855-accelerometer-problem.html
http://www.htc.com/au/faqs.aspx?p_id=267&cat=0&id=94110
Problem solved and all working well again. It does, however, point to the fact that an app can crash the OS, which is not, imho, that good.