As I'm only using SD-Video quality I only can Guess.
You say that it has worked ?
Progressive - can be a of the problems in many ways - one of them is that it needs LOT'S of Space - so
• How much free space is there on Your "BOOT" Start-Up (Mac OS) Hard Disk (other's do not count) ?
For SD-Video - My minimum of free space on THIS Hard Drive is 25GB
For HD-Material my guess is that 4-5 times more should be enough to let application and Mac OS run OK. As Mac OS X is UNIX it also behaves like that and produces lot's of .temp files and they can not be addressed elsewhere so external hard disks can not take care of this at all - The Space must be on Macintosh HD (or what You called it)
Yours Bengt W
Then I would try - just to in-circle the possibly culprit
• Start a new User Account (Apple-menu / System Pref. / Accounts / Plus sign)
• Log out of this Account and into the New one (Apple-menu down to las option)
• Now start iMovie and import some material and re-try Share function
If this now works - then my Guess is that the problem is in
• iMovie pref file/s - or -
• iMovie Casche files
in the old account - and that trashing them will be the medicine (as iMovie now has to create New and error free ones)
This is a very common problem - most often due to - Panic/Forced Quits - as they induces errors in lot's of places ( finally adding up to a Major Break-down ). So by
• Trashing these files
• Running - Repair Permissions (Disk Util tool)
• Running - Repair Hard Disk (Disk Util tool - but now You first has to start Mac from DVD or ext. Hard Disk)
I can keep this Major problem away as long as possibly.
(and only Force Quit - when there are no other option (as just waiting it out)
Yours Bengt W