I have all the requirements- XP, 1GB Ram, and 2GB of free hard disk space, yet Firefox crashes many times. And each time I have to download it again, is becoming a menace.
If you are running Firefox 3.0.1, you are using an extremely outdated version of Firefox that does have many known crashes.
If you go to www.getfirefox.com, and download Firefox 13. Then, use the Firefox Reset feature, does that help you crashes? Refresh Firefox - reset add-ons and settings
Also, try reading Firefox crashes - Troubleshoot, prevent and get help fixing crashes