Why is there randomly a small blue clock on my audio files in Windows Live Movie Maker that stops them from working

I have been working on movie maker for a long time and have been working on this project since like 6 months ago and yet have i seen movie maker just randomly put a blue clock on my audio files that stops me from hearing them. I've tried waiting an hour and more for the blue clock to go off of my audio files but nothing is working, please help me .I need to finish this video but I can't do it with movie maker acting up like this! I will do anything for help.