Mcafee poped up telling me that Plugin Container for Firefox wants to access to the Internet, do I allow it or do I block it?

Firefox seems to crash alot for me and when it does a window pops up telling me the problem is with my Plugin Container for firefox. I have uninstalled Firefox many times and than installed the new version. Well today my McAfee popped up and told me that the program Plugin Container for Firefox want to access the Internet. Either I can allow it, allow it once or block it. I do not know what I should do.