Finishing/rendering/exporting film

Hi Folks,

I made a 36min film in iMovie - which I could not 'finish' due to repeated error messages. I had to leave it alone for a bit -

But it is a really important piece of work; I am not a film maker, but the subject matter is important.

I understood the initial problem to be disc space, so I went into the Apple store - was sold a large external drive and moved the whole film project onto it. I did encounter some difficult issues here, whereby at first the project could not find source clips, but I re did the whole process, and restored everything, and it is perfectly possible to play the film through as a project in iMovie.

I tried to finish it again, and the same error came up.

After spending time in discussion forums (which I confess are often at a slightly too high skill level for me) I tried to simply export to QuickTime Player - understanding that a degree of finishing happens in this quicker and perfectly efficient process.

The export starts, and after around forty minutes I get a (-108) error message - there are 24gb of space free out of 60gb on the machine itself and 940gb out of 1000gb on the external drive to which I have now moved the whole project. The project in question is 22mb.

I feel defeated, and need to be able to go somewhere for somebody more skilled than me to help - most of all because I made this film about a friend's work, and it is really important and needed.

Any suggestions for being able to get a finished film to my friend would be very very much appreciated, preferably simply explained :-)