If I print a webpage from Firefox 3.6.6 to my HP deskjet 990cxi printer (USB connection), the text is printed normally, but the images are reversed (mirror image).
This hasn't always happened, but seems to have been a "feature" of at least the last few versions of Firefox.
If I select the print option for Mirror Image then the image is OK, but the text is reversed.
I've seen a few other posts scattered over the web from people with the same issue, but no sign of a cause or solution. eg http://support.mozilla.com/en-US/forum/1/378421
By the way, the problem doesn't happen with IE 7