Een van de antwoorden die ik voor je heb kunnen Googlen (bleek helemaal niet moeilijk te zijn overigens.)
The cause of this problem in most cases is the project asset that that the timeline is on has been moved or is missing.
Here are some examples of missing assets:
· Still image files like JPG and BMP files
· Video clips
· Custom titles or Menus
Any of these items will cause this problem if they were in one location on the hard drive and moved to another. Studio will search for missing media whenever a project is opened. So if you have missing media, close the project and open it again.
If closing and opening the project does not help, please try and move the files back to the original location.
In some cases it may be caused by a removable drive coming back with another drive letter. If you cannot change the drive letter back or do not know what the letter was then follow the steps below.
Delete any part of the project that has the blue exclamation point.
Copy the whole project on the time line.
Go to File, then new project.
Now paste your project into the new project
Now add the images and titles you had to remove in the old project.
'Future proof' (de; v) Verschijnsel waarbij men een dure aankoop rechtvaardigt door innovatie te negeren