The site was hacked so there are several thousand "viagra" (and other drugs) pages that were indexed. I've removed the hack so the pages don't exist any longer but Google had already indexed them so they are appearing as missing pages in my webmaster account.
All of the pages end in .html (there are no other .html pages on the site) so I can use that in the .htaccess - I just wasn't able to figure out specifically how to do it (I'm not good with regular expressions and I couldn't find an exact fix in Google).
I tried the link you supplied above, but wasn't able to get any of the examples working. The one below seems to be close (It changes all .html to .php):
RedirectMatch 301 (.*)\.html$ http://www.example.com$1.php
I edited it to try to redirect everything to the home page but it returned an endless loop error in my browser.
Any other ideas would be appreciated.
Thanks in advance,