Well, that it started shows you have all perquisites installed. Newest is 2.42.9 so not sure what you are running though it appears to be 15 odd years old.
Enter about: in the URL field and enter. Copy and paste the user agent string here.
Things to try, open SeaMonkey, go to Help-->Restart with Add-ons disabled and retest. Try a different profile, Tools-->Switch profile will bring up the profile manager where you can create a test profile.