Frenzo's solution worked for me - went to System Preferences and turned off Time Machine. THANK YOU !!!!!!
MY DETAILS:
In case it matters to anyone having this problem later…
I had the same problem as the op… Share -> Export using Quicktime… Save to Desktop. It said "Exporting Project…" for the usual long time but the file is never created.
Machine Specs:
iMovie '11 on Lion 10.7.5 installed on a MacBook Pro with no external drives connected and plenty of free space.
Source Video:
QuickTime Movie in XDCAM codec from JVC HM-150U
Shot in SD 720x480 16:9 60i
4ea ~4GB clips at 30,308 kbps approx 16min each from a ~1hr event
Codecs listed in Info is DV/DVCPRO - NTSC
Export Settings:
H.264 30fps, 2222 kbits/sec, 960x540 (Current), Single Pass, Deinterlace, saved to Desktop
My Testing Attempts:
It said "Exporting…" until the usual Progress Bar ended. The file was nowhere to be found. I checked iMovie project folder (Movies -> iMovie Projects -> xx.rcproject) and did a full disk Spotlight search with the very unique name - nothing.
I did a project Duplicate, deleted 3 of the 4 clips in the project, then cropped the remaining one down to 30 seconds. It processed fine. Undo crop and re-crop to 5 min and it still worked. 8 minutes - good. But 10 minutes? No. The whole 16 minute clip? No.
My Findings:
At the end of each run, when the Progress Bar ends with "less than one minute…" then stops, there is second fast Progress Bar that appears also saying "Exporting Project…" As soon as this appears, an icon appears in Finder in the proper folder with the full name of the exported movie but the icon is not a thumbnail but a generic movie icon. When the second Progress Bar finishes, the movie icon is replaced with a thumbnail taken from the movie, and all is now good in the world.
What I believe is happening is that during exporting, iMovie is building a hidden, temp file somewhere in HD -> Users -> Username (I watched the folder size grow as it processed). When exporting is complete and the file is ready, it copies the temp file to the proper destination folder then deletes the temp file. This process would explain the second short Progress Bar. If the project is small enough (under 8 minutes in my case) this transfer happened so fast that it apparently didn't need the second Progress Bar - the clip just appeared.
I also opened Activity Monitor and watched the Disk Activity - Data graph. It performed Read at a fairly high rate, and had occasional Write spikes at a lower rate every 15 sec or so. Makes sense - it's reading a file at 35,000 kbps and compressing it down to 2,222 kbps, so the CPU reads a bunch, crunches it, then spits a smaller bit back out to disk.
THANK YOU FRENZO !!!!!!!
-ScubaJon