Unable to launch Firefox

Hello,
I am unable to launch Firefox. I am running Windows XP.

It was working just fine last night when I used it last. I never changed, added or deleted anything! This morning when I turned my computer on, I went into IE to perform a few tasks (which I do regularly like clockwork). During the time I was in IE, a message box popped up and said that Windows had downloaded new updates and asked if I wanted to restart my computer. I chose the option 'restart later', until I had finished what I was currently working on. When I was finished, I turned my computer off and started it back up again. This time, I attempted to go into Firefox, but it wouldn't let me access it. I click on the icon on my desktop and all I get is an arrow pointer and an hourglass .......for about 20 seconds then.......nothing! I am the only one in my house, and the only one that has access to my computer, so I am POSITIVE that no changes have been made that I am not aware of. I've searched Firefox and Windows sites and can't find anything that can help me. Actually, I'm not certain that the Windows Updates have anything to do with me not able to launch Firefox....maybe it's just a coincidence. Can someone help me please???