Can`t start Mozilla

[Rafael Sasaki <sasaki@solar.com.br>]

Hi,
 I have a problem with Mozilla. It started yesterday, and I cannot start Mozilla
anymore. Every time I call it I receive this message:

	The program must close to allow a previous installation attempt to
	complete. Please restart.

 and the application does not starts. I don`t know how to stop this message
and the 'previous installation' never completes. I have already rebooted my 
computer, but it happened again.
 Does anybody can help me please?

thank you,
  Rafael Sasaki