Without knowing what model of mac or year of your computer or version of OS X you are using or version of iMovie you are using....I will be guessing.
I will assume you have checked your hard drive and there is plenty of free space. Also is there a possibility that you may have been storing and/or saving iMovie projects on a drive that is no longer available or attached to the computer?
If all the above is not applicable thy this - Open Finder, find your Movie folder and right click on it, select "get info". Go to the bottom of the window that opens to Sharing and Permissions. Make sure the account you are using has read and write permissions - if not you can change them by looking under the privilege column, click on the privileges for the user name and change it to read & write. You will have to click on the little lock in the bottom right corner and put in your admin password.
Hope this helps.
Lisa
Thanx Lisa
Please excuse if this is confusing - I am not a wizard in this area. A short history:
I thought my iMovie activity was being housed on an external hard drive (Called G drive). This morning I looked at my project list in iMovie and deleted 5 old projects to free up space. I thought (but not certain) they were on the G drive. After I created this thread this morning I tried again to create a new project and it worked but it was in the iMac hard drive, not the G drive. After reading your response I looked at the iMac hard drive, right clicked the movie folder, and saw (next to my name) read and write permission. I then looked in the G Drive where there is no "Movie" folder but there are 2 folders "iMovie events" and "iMovie projects". Clicking on the events folder reveals all the events I see when I go to the iMovie program but there was nothing in the projects folder.
I then right clicked the "iMovie projects" folder, get info and saw a read only next to "unknown" (not my name). I changed that to Read and write. and then tried (in iMovie) to drag the project from the hard drive to the G drive but got an error message.
Next I went back to the G drive iMovie project folder permissions and saw a "staff' listing which was also read only. Changed that to read and write and was then able to drag the project in iMovie from the hard drive to the G drive.
This raises a few questions
1) Why is there a Movies folder in the iMac hard drive but not in the G drive?
2) Why are there a iMovie events and iMovie projects folders in the G drive
3) Why under the permissions on hard drive > Movies is there a listing with my name but in G drive > iMovie projects it is called "unknown" and why a listing called "staff"?
I know this is very confusing. It appears I now have a project in the G drive > iMovie projects folder but I don't know why. Also, how does the program know where to create a project the next time i want to create one?
Thank you for your help and especially for your patience
poppi