Finding your profile is the first step in a lot of fixes and tweaks for Mozilla. Instructions on doing this should be in the release notes for your release of Mozilla. Here are some more general instructions:
Your profile should be in .mozilla, which is in your home directory
Depends on your Windows version and age of installation. May be in /windows/Mozilla , /windows/Application Data/Mozilla, or /Documents and Settings/(user)/Application Data/Mozilla. If you are using Search to find your profile, make sure to include both system and hidden files (these default to excluded), otherwise your profile won't be found.
~/Library/Mozilla/
Search for *.slt
Windows XP, in its infinite wisdom, sometimes decided to install on a different drive or partition when you upgrade to it. This means your profile will be in an exciting new location.
Use the "contact" link on the left to pester me.
Find out more about Mozilla profiles