Firefox won't open except in Safemode

Question

When I clicked to open Firefox a few days ago, a little window opened with this message:
''A script on this page may be busy, or it may have stopped responding. You can stop the script now or you can continue to see if the script will complete.
Script: file:///C:/Program%20Files/Mozilla%20Firefox/components/nsExtensionManager.js:623
I found the solution page about this at Firefox and followed the instructions - closed FF, opened in Safe-Mode, went to Add-ons and changed my theme to the default one.
Then I closed FF and re-opened it.
The solution worked. (yay)
Later, though, I had the same problem when I tried to open Firefox again.
I went through the steps of opening Safe-Mode but my theme was already the default so I changed it to another then changed back to default, closed FF and then re-opened.
When I had the same problem yet again, I went through the above step and then uninstalled all themes but the default. (Or so I thought).
The next time I tried to open FF, the same ole error message came up. I did the fix in Safe-Mode, closed FF then re-opened.
However, a different message came up:
'''FLAGFOX VERSION: null (missing IPDB!)
ERROR MESSAGE: Fatal Flagfox startup error!
EXCEPTION THROWN: TypeError: ExtensionManager.getItemForID(id) is null
STACK TRACE: startup()@file:///C:/Users/Donna/AppData/Roaming/Mozilla/Firefox/Profiles/ilt58l3p.default/extensions/%7B1018e4d6-728f-4b20-ad56-37578a4de76b%7D/chrome/flagfox/modules/flagfox.jsm:40
([object ChromeWindow])@file:///C:/Users/Donna/AppData/Roaming/Mozilla/Firefox/Profiles/ilt58l3p.default/extensions/%7B1018e4d6-728f-4b20-ad56-37578a4de76b%7D/chrome/flagfox/modules/flagfox.jsm:159
Flagfox_loadForThisWindow([object Event])@chrome://flagfox/content/overlay.xul:16
BROWSER: Mozilla Firefox 3.6.8/20100722155716 (Gecko 1.9.2.8/20100722155716) using locale en-US on WINNT x86-msvc''''
Ugh.
There was a link to click on but, before I could click on it, another window opened with that old error:
''A script on this page may be busy, or it may have stopped responding. You can stop the script now or you can continue to see if the script will complete.
Script: file:///C:/Program%20Files/Mozilla%20Firefox/components/nsExtensionManager.js:623
So I couldn't click on the link for the Flagfox error because I had to close the 2 windows in order to go to FF Safe-Mode to get rid of the Add-ons/Themes error.
After closing then opening FF again, it opens but hangs. At one point, I had dinner then came back and it was still hanging. So, I opened Task Manager to End Task in FF to close it.
A few weeks ago, I'd installed Chrome. Since I saw "ChromeWindow" in the Flagfox error, I thought perhaps Chrome was messing up FF so I uninstalled Chrome, shut down and turned on my computer again.
Then I tried to open FF, only to have both errors pop up again.
BTW, after opening FF in Safe-Mode (for the zillionth time), I went to "themes" and all of them were there - I thought I'd uninstalled all except the default but they were all there.
The furthest (farthest?) I've come is to be able to click on the FlagFox link which opens FF but then this comes up:
flagfox.servehttp.com is taking too long to respond
and FF hangs... and hangs...
I'm so frustrated!
So, I can only open FF in Safe-Mode.
I came here to the forum and logged in, etc. in order to post this message but none of the Question/Details boxes were visible so I'm currently using Opera.
I would appreciate any help. Please keep in mind that I'm not 12 years old so I don't know much about computers, lol. In other words, please respond with simple and easy words so I'll understand.
Thanks!

Answer 1

Thank you, thank you, thank you!
I uninstalled it, closed FF in Safe-Mode, reopened it and, ta da!
THANK YOU!