It seems you're not the only one experiencing this with some sites. Pop over to the Mozilla forums and use the 'Advanced' search option. Type in, 'prints and first and page' (the 'and' makes the search look for posts containing all those words).
It looks like it's a bug that's been around for a while (there are descriptions about it to be found). Since Firefox doesn't have this problem with all sites, perhaps some alteration of the sandhill.com site might help? I use a Firefox extension called HTML Validator. According to this, the sandhill page has 0 errors and 31 warnings. Maybe it's one or more of the 'warnings' that are making the difference. Perhaps try examining a site that doesn't
have the print problem and see what the difference(s) are with this one.
I don't know if this utility would be a help if you want to keep the presentation of the site as it is (most sites that look OK have errors according to HTML Validator's standards). But perhaps rectifying some of any errors HTML Trim finds might make a difference to the print problem.
Just one point. The utility rectifies some errors it finds without warning, so if you do run it on a web page, make sure the 'backup' option is ticked, or that there are other backups (I'm sure you've got this covered anyway but thought it just worth a mention).