firefox does not open when i click its icon i see the hourglass/system busy cursor but after that nothing happens when i chec out the task manager it shows firefox.exe in its processes but cpu usage remains 0
what to do
what to do
firefox problems
Maybe some extension is preventing it to open by creating conflicts.. try ff's safeboot option and see if it opens.. else re-install 
Happens to me sometimes. Jus right-click on the process and "End process tree" and start the ff again. If it doesn't help, create yourself a new profile.
reinstall it clean ur registry using the reg cleaner 4.3 or any reg cleaning software and then try reinstalling it