I can't help directly... but some saved links to read
Error Compiling Movie http://kb2.adobe.com/cps/906/cpsid_90670.html
It's tough with an Unknown Error simply because it's unknown.
What you might try just to get the job done is bring in the already exported MOV and just add the lower third to that instead.
I trashed prefs and its opening slower. It still has the same error on render.
I am gonna jump back to cs5 cause i have had quite a few problems with cs6.
Hopefully i can edit in Pr cs5 and get effects in Ae cs6 for future projects.
It could very well the drive its a 5year old enterprise hitachi. It seems to take everything else well and i rebuild the drive with disk warrior once or twice every year. I may just make the back up drive the main and replace the backup.
Anyway, i am gonna open this in cs5. I wonder if there is a way of using an xml to reconstruct the SEQ in cs5, with all the DLink stuff in it also.