I’ve been trying to work on a film shot in XDCAM EX and have been tearing my hair out as it crashed every few minutes when I was playing back footage. I found this thread and tried some of the solutions, and it turned out to be something similar to the BPAV1 problem noted above.
All my files were indeed in BPAV files that didn’t have any naming problems, but when I imported the footage, I dumped an entire folder containing multiple subfolders and BPAV files inside of it into Premiere. This was the cause of the constant crashing, as I tried importing single BPAV folders, one at a time, and the problem was solved.
Adobe really needs to make their XDCAM EX support more stable, as this little oversight caused my entire system to crash constantly. Thanks to everybody who put their solutions up here!
(I use Premiere Pro CS4 on a Windows 7 machine with an i7 2.66ghz processor and 6 gig of memory.)