I cannot update my Firefox 3.5.2! The "Check for Updates" option under "Help" is greyed out, even though I am an administrator on my computer. My preferences are set to automatically notify me of updates, but no matter how many times I restart Firefox or my computer, it never brings up a window telling me I have updates available. I would really rather update this version that have to install the whole thing over again which is a huge pain. What can I do??