Are you using Yahoo Messenger in a browser like Firefox, or are you running a application on your computer?

i am running an application

i can run it on my lap top it goes through , we uninstalled it reinstalled it it worked fine but then i closed yahoo messenger and it wouldnt let me sign on

So let me get this straight. You downloaded an intallation file for Yahoo Measenger with a browser, ran it and installed the program. Now it doesn't work, right? If this sounds right, this has nothing to do with Firefox. You'll have to consult Yahoo Support. If it installed a plugin so you could use extra features or something on a Yahoo Messenger page (this is pretty unlikely), this has to do with Firefox but you should still head over to Yahoo Support instead of here.