Firefox multiple rowed textbox getting auotmatically filled in with some url like junk data

We have an intranet php application developed for Firefox and it was running fine for almost 2 years. Now, for the last few days, the multiple-rowed textboxes are often getting filled in with some url like junk data. Sometimes, this happens only when you click on the textbox.

But开发者_如何学C when we ran the application in Google Chrome, we didn't face any problem. Is this anything to do with a firefox virus?

Please help.

This problem didn't go even we reinstalled the Firefox browser. Finally, we reformatted the system. Firefox is now working okay.