Crash opening .html files

Are any crash dumps created matching the times of the crashes? If so, please zip them (only the ones you know are due to this) and email them to leo@gpsoft.com.au

It may also be worth a try to set another browser as the default web browser, to see if the problem still happens or is specific to a certain browser. (It's also possible that restoring the original browser then makes it work, if the issue was something weird in the registry which was repaired by re-assigning the defaults.)