Brendan,
No ideas except to check the true code. Sometimes, if you are
entering in line format changes, RoboHelp may not clean up some
tags and you may have duplicates or competing tags, e.g. <SPAN
STYLE = "whatever"><FONT = "something different>. If this
is happening in a lot of places, you need to rethink how you handle
format changes.
For IE users, here is a true story:
Internet Explorer wouldn't connect to the internet. We could
access the internet from the MyComputer/Favorites tab but it
wouldn't show all multimedia content. IE always gave a "page cannot
be displayed" page. I was totally baffled so decided I would try
Microsoft's paid support. They had me download and try Firefox.
When that worked, they closed the issue and wouldn't continue to
troubleshoot. So, the official Microsoft position seems to be to
use Firefox.
Hopefully, you won't have to resort to that for your
users...
John