My Mozzilla Firefox wont start up?

Okay so i log onto my computer and i wanna go to firefox but it will not load up and then all the sudden it crashes and the bottom bar goes really old looking like what we had on our old one. so i just restart it and then it comes back up normal. but firefox still isnt working. so im like crap cause all my passwords and stuff are saved on there so i keep on trying and try to re download it and everything but nothing works. i have a windows vista also. so then i scan for viruses and i have a couple of adware but i delete all those and then try it and nothing different. So then, i check my windows updates to see whats going on cause maybe the computer crash in the beginning caused it and there is three "important updates" 2 of them are for security and 1 is for internet 9. so i figured the internet 9 is whats causing this but the problem is NONE OF THEM WILL DOWNLOAD it gets about 3/4 there then it just shuts down and says failure to instal and im just like wow. so idk if i have a virus or what cause its starting to piss me off ive been up five hours trying to fix it and ive scanned it twice! if anyone has anything thats worked for them id love to know cause this is starting to really bug me cause i want my internet back. plus itunes wont load up! so please help me out. thank you!!!!!