Can you check your Java version @ http://browserspy.dk/java.php or on the Plugins Check page.

You may need to update it to address that problem.

I believe it is up to date. The version is: 1.6.0_24 .

OK, could you check the troubleshooting steps in this document please: Websites look wrong or appear differently than they should

I looked on there, but it's not really about websites looking wrong. Basically, it's a Gmail thing. When I type a name in the address field on a new email, the suggested contacts/addressees are not appearing clearly. They look like they are all there, but stacked on top of each other. Make sense?

Yes, I've seen that before myself. Maybe try this one.

Go to Tools | Options | Content and click the Advanced button in the Fonts & Colors menu. Then uncheck "Allow websites to choose their own fonts instead of my selections above".

I found that option in Firefox preferences (not Tools, it's not in there)...Unchecked it, but didn't help. Man, this is a bummer.

What do you mean with jumbled?

Do you mean that the list is not sorted or don't you see readable text?

It is possible that there is a problem with the file that stores the "Saved Form" data.
Rename or delete formhistory.sqlite (plus formhistory.sqlite-journal and formhistory.sqlite.corrupt, if they exist) in the Profile Folder in case there is a problem with the file that stores the "Saved Form" data.
This will remove all saved form data, so you may want to rename formhistory.sqlite to formhistory.sqlite.sav or move the file to another folder in case you need to recover some saved data.

Help > Troubleshooting Information > Profile Directory: Open Containing Folder

Yes, by jumbled I mean that the list appears to be stacked on top of each other...I've attached an image...

I will try what you suggested as well..Thanks to everyone for the help, BTW!