Preview taking a long time

 I am currently converting training modules from powerpoint presentations to .STORY files. Throughout this process, I am adding voices (.mp3 formats) for each slide, and a quiz at the end of each presentation. I have been having issues when previewing my .STORY files. Randomly, the files will stop letting me preview them (They get hung up on the very last slide. For example, Preparing slide 38 of 38). When this happens, I have taken the suggestions seen on this forum, and imported the file into a new file and it works fine for awhile, but then it stops working again. This has happened to me on numerous occasions, with numerous different files. I am working locally (on my C: drive), my directory path is less than 260 characters, and I do not have special characters in the file name. Any help would be appreciated.

Thanks.

Tyler