If you use Firefox, it is time to update to 18.104.22.168.
It is released on May 30, 2007. Your Firefox may auto update itself or not.
Click Help > Check for Updates to get the update.
This update will fix following security issues.
XUL Popup Spoofing
XSS using addEventListener
Path Abuse in Cookies
Persistent Autocomplete Denial of Service
Crashes with evidence of memory corruption (rv:22.214.171.124/126.96.36.199)
And provide better Windows Vista support.
And also provide two more language Afrikaans (af) and Belarusian (be).
Just for the security issues, it is worth to update your Firefox.