Yes, the html2image.exe is the WAS Preview engine.
the incoming connections will be coming from the loop back address:
127.0.0.1
it's safe to click allow.
As for the connection issue, I had a similar problem recently that turned out to be a problem with one of the Add In's i had installed in Fire Fox.
I uninstalled all Add In's, the installed only Fire Bug and Web Developer toolkit and the problem went away.