Movie Maker Split Tool Deletes half the project

OK! So I'm a gaming youtuber and I've noticed recently while i'm editing some of my videos, when I try to use the 'Split' tool, it will glitch out and instead of splitting it will just delete a huge chunk of my video... and it doesnt even delete up to the poihnt i wanted, it removes everything up to the previous split I made. why is this happening and how can I fix it as I am getting rather irritated. I saved my project, closed movie maker and reloaded it, and the same thing happens again. i start a new project and it's fine. it seems to happen to projects beyond a certain length, my shorter videos have been fine, but recently a couple of my longer recordings (ones that desperately needed the split tool to cut some of the footage and reduce the video length) have been having this glitch. i use the split tool several times and it's fine and suddenly no matter where I try to split it just removes like half my video. HELP!!!!