Production Premium CS5 has always worked fine for editing DV content. But I've just graduated to AVCHD format (from and Olympus OM-D E-M5), and have problems with scrubbing and been unable export reliably. The common thread seems to be that, when things go awry, the "Adobe QT32 Server.exe" is chewing large amounts of CPU and never exits. Sometimes Premiere crashes, sometimes it just hangs (Not Responsive) and I have to kill it.

It's a pretty simple experiment: I have about 35 minutes of clips. I automate them to the timeline. Problem 1:

• Most of the clips display properly in the timeline, with a thumbnail. But some just display a green square. A few clips after the green square also show no thumbnail.
• I don't believe it's the source material. Frequently, the problem shows up on the same clips. But sometimes not. I've put the affected clips into their own timeline, and they display fine. All the clips play fine in the Source window.
• I've tried with Mercury playback enabled or disabled. No effect.

Problem 2:

• Scrubbing works fine for awhile, then stops. Wait a minute, and scrubbing works again. "Adobe QT32 Server.exe" is chewing 13% or so of CPU.
• If I close or kill premiere, the server stays running, and I need to kill it.
• The clips with the green thumbnails are no different than the others, when scrubbing.

Problem 3, Exporting via the media encoder:

• Chugs along fine, for 5-10 minutes. Then the preview window goes green. A few minutes later, the export fails with "Unknown error".
• It's completely random. I've watched to see where the problem starts, then split the timeline before the problem. Retry with the new, shorter timeline, and it crashes in a different spot.
• Again, "Adobe QT32 Server.exe" is chewing CPU, and often it doesn't exit when I close the media encoder.

The machine is an i7-960 with 24G of RAM, and an Nvidia GeForce 560 Ti. Lots of RAM and CPU. Several disks, but no RAID. I've tried moving the media cache to SSD - no change.

As I say, I've turned Mercury on/off, with no effect.

I've completely deregistered, uninstalled, restarted computer, reinstalled, reregistered CS5. No effect.

Aaargh!