If you are seeing the same thing in multiple different browsers, the "problem" is more than likely with the web page. If you see a print-related problem only in Firefox, it's probably a printing Bug in Firefox or the core Gecko code - there's 3 or 4 Bugs that have been around for many years that have been causing a lot of grief for many users, myself included. One such Bug was fixed just last week for Firefox 4.0, like 8 1/2 years after it was first filed.

1. HP is responsible for keeping their Smart Web Printing program up to date with Firefox as Mozilla comes out with new versions. Last spring, like 3 months after 3.6 was released, I figured that we would never see a version that was compatible with 3.6 - HP has done that before, skipping an entire Firefox release version or taking so long to come up with it that the next Firefox major version was about to be released. It's like they do their QA based upon the level of customer complaints, instead of actually testing their applications with the most popular programs their customers are using.

2. Some web pages use a print.css file (or other page coding like @media or @import) to send a different format of the page to the printer vs. what is displayed on the screen.
http://www.w3.org/TR/CSS2/media.html

3. I haven't been looking at XHTML vs. HTML when viewing specific pages that users post links for when they are looking for help with printing a specific web page, but it might be that when coding an XHTML page it is easier or makes more sense to provide specific content for "print" vs. "screen". There's no point in printing full-width headers and banners, along with website navigation menus and advertising - leave the width of the printed page for content.

4. Browsers sometimes format pages for printing differently from other browsers. Last week I was trying to troubleshoot a printing problem for another user here and one page he linked looked different in Print Preview in IE8, Opera 10.61, Chromium 7.0.507.0, Safari 5.0.1, and Firefox 3.6.10, and Firefox 4.0b6 - 6 browsers and 6 different page formats - not even the two versions of Firefox looked the same. That particular page was being displayed in Quirks Mode (didn't meet W3C standards), which is where the browser has to guess what the author of that page was thinking, and didn't use a print.css file or @media tag for print.

4. In conclusion, I print nothing in any browser without doing a Print Preview first, I am tired of wasting paper and ink on poorly formatted printed pages - regardless of whether the problem is with the web page or the browser. Firefox doesn't make that easy, no context menu item for Print - Print Preview like some browsers have; but there is an extension that adds those context menu items. - https://addons.mozilla.org/en-US/firefox/addon/1778/

Thanks very much for your reply and info. I had no idea of the complexity of what was going on 'under the hood'. I had thought that by now printer drivers would understand HTML or its improvements. So did they just wriggle out of doing it?

Thanks for the addon info . I've been using the File drop-down instead which does the same with two clicks like this addon. So it's about even!