Could you check the address bar of the page that says you need to update? If the address bar isn't visible, try pressing the Esc key to cancel website full screen. Is it a Mozilla site or is it someone else's site? There are unfortunately many attack sites that try to force you to download and install programs which are harmful. We can provide tips on checking/cleaning your Firefox and your Windows. At the system level, a good first step is to run some effective malware cleaners. This article lists free programs others have found useful to supplement your existing security software: [[Troubleshoot Firefox issues caused by malware]].