What version of Music Maker?

What are your computer specifications, Windows version, RAM, Processor, Sound Card?

I think it might be a resource issue based on maybe driver compatibility,  or you are recording vocals onto a project that has a lot of things that need processed.

If you have a heavy load project, you might want to try exporting the project as a WAV file then creating a new project, load the WAV file and then record your vocals... this should cause less taxing on the system. Once recorded, you can then import the recording into the original project.