Yesterday I was able to run MVT to verify a message reported elsewhere about a SiteAdvisor process not running.
Today there were two major updates - of SiteAdvisor (to 3.1.139), and of McAfee programs (to 12.8). I went to the MVT download centre to get the latest version and after some installation problems I uninstalled MVT and re-installed it.
Now, MVT crashes every time I try to run it on this machine. Every time. Works fine on Windows 7 though so it's not so much of a problem (or rather, it's a problem that will eventually fade away)