Exporting/Sharing trouble that I wasn't having a few weeks ago

I'm trying to export a movie, there are no missing clips, my "Share" is lit up and allows me to go through the motions as if I am exporting a file but then no file appears wherever I designate it to go. If I restart my computer it will occasionally make a TEMP .mov file thats like 48kb but it will not render a proper movie for me. It was working fine last time I exported the project in April but now no luck. Any suggestions?