I cannot open project; do I start all over, or is there hope?

Question

So I have started doing video podcasts and am using iMovie '11 for editing the footage.
I exported my first episode which turned out to be around 18 min total. When I watched it to verify, the audio started becoming out of sync with the video. It got progressively worse. Searching these forums and the Internet, I found other users were noticing the same problem. One workaround was to extract the audio from each and every clip. I tried this and it worked. The exported movie had no video/audio sync problems. So I thought that would be my workflow.
Then I started working on my second episode. It turned out to be a long one clocking in at an hour and 45 min. It consisted of some complicated edits and a very large number of separate clips. I started my tedious workflow and workaround of extracting the audio from each and every clip so the exported movie would have video/audio in sync. The process got progressively slower and slower. At some point about halfway through, when I right clicked on an clip to extract the audio, the spinning beach ball came up and iMovie hung. I restarted and tried again, but the same result. When I restarted again, iMovie would not start. I can double click my first episode project and open it, but the second episode will not load; well, it will load sometimes, but if I do anything with it, including just moving the mouse, spinning beach ball and hung. Searching the Internet, I found recommendations to clear the cache and plist. This didn't help any for me. Sometimes, iMovie will hang when I simply select the project in my project library; sometimes, I can select the project and quickly get to the menus. I tried doing this and duplicating the project, but the duplicated project showed the same symptoms.
Unfortunately, I did not keep backups and I don't know why I didn't with such a large project. I've learned my lesson.
Question: Is there any hope of getting the project to a state where I can salvage it? Anyway to reattach the audio outside of iMovie or something?
I also realize now that iMovie is probably not meant for such large, complex projects. But, the video/audio sync issue doesn't seem to be that hard to reproduce. I have submitted feedback for that.
If I decide to continue using iMovie, I am going to add to my workflow that a project cannot be over x minutes long, export the parts, and combine them with Quicktime.
Question: Are there recommended guidelines for a single project's complexity or length?
I am hoping for some answers here; otherwise, I guess I'll have to start all over and spend the next two days re-editing.

Answer 1

I have the exact same problem here Jason, only in my case the project is merely 15 mins long...
I noticed the audio sync issues on exported files (needed it as a QT HD to play in front of a whole school assembly) about half way through the audio would go miles out - well over a minute adrift.
Having read some posts I decided to detach the audio as you did, it let me do this for a while then about half way through I got the beach ball and likewise I'm now stuck with an urgent essential project that I can't do anything with. This is on a brand new 27" i7 iMac with all the updates, and no other projects. It's like the dark days of Pinnacle on windows, I thought this stuff was supposed to just work!
Does anyone have any suggestions on a fix - I've repaired permissions, tried trashing the iMovie prefs etc but it still hangs every time.