Windows Movie Maker – not enough memory

For over a year I have been using Windows Movie Maker to edit videos. For about 4 months, the videos were filmed on an iPhone. For the past 8 months, they have been filmed on a Cannon Rebel T3i camera. The saving and publishing has been for the most part seemless until this month when videos are unable to be exported from WMM and a message appears claiming there is not enough memory and to save at a lower resolution. There is plenty of memory on my computer and I have tried saving it both in different locations and with different names with the lowest possible resolution and nothing works. I have Windows 7 and I have never updated my WMM since I bought my computer in 2012. I am frustrated with the apparent problem on Microsoft's end and I want to know ways to publish my movie.