Welcome to Bleeping Computer!
What version of Firefox is installed? To find out click on Help
then About Firefox
in the menu bar. You'll find the version displayed there.
When I go to certain sites (one in particular, though I believe it happened to another one earlier today) it loads wrong. Everything is out of alignment and disorganized, I think most people using computers have seen something similar either because of something blocking parts of the site or internet issues, but this continually happens despite refreshing. The site just loads wrong when I am using firefox. I popped up windows IE and it loaded like it should there.
I've never come across this issue myself though helped someone not long ago with a similar issue and after days of trouble shooting found that it turned out to be his K9 Web Protection. Do you have any Parental Controls installed?
You could also try starting Firefox in safe mode to see if that makes a difference. Please do not confuse this with Windows Safe Mode. Not the same.
See link below on how to do that:Firefox Safe Mode
If I may ask, who guided you with removing the rootkit? Are you sure the computer is clean? Did you have this problem before the rootkit or just there after? If you'd like to verify that your computer is clean, you could start a thread here
and have a professional have a look. If you do, please explain in detail and add a link to this thread.
Please stay tuned. Other members may have some suggestions as well.