Do not use periods in your project name.
iMovie ’08: Don't use periods in project name
In iMovie ’08, when you create a project name that contains a period ("."), the period and all subsequent characters following the period in the title name are not displayed.
For example, if you name your project "My Vacation.Hawaii" the title will be listed as "My Vacation"—the period and all subsequent characters are not shown.
If the project is named with a period followed by a space, it may no longer open properly in iMovie. Instead, it may appear as a folder in the project list.