First of all, I'm not sure FrontPage is truly compatible with Vista. Microsoft stopped producing and supporting FrontPage before they developed Vista, so the two programs are most likely going to have issues together. It's the same deal as trying to use Adobe PageMaker on Vista. It will probably work, but there are going to be issues.
Secondly, I found a tech site that seems to have an answer to your particular error (not saying for sure that more errors won't pop up when you get that solved, though, unfortunately). Try the solution mentioned at
FAQ