[Paul Jay]

As Shane said:

Frame Controls: Automatically selected: Off

That’s ABSOLUTELY your main issue

In my opinion HD to SD always needs resize filter to BEST to look good in Compressor.
Especially when your source has a codec like HDV or XDCAM EX.

[Paul Jay]

Try a SATA board if you want that 145;)

[Paul Jay]

I believe that Telestream Episode can create VC1 movies.

[Paul Jay]

Try copy/paste timeline in ProRes timeline with same settings.

[Paul Jay]

Create a copy of your project too, so you still have your version 6 project.

[Paul Jay]

Trash your finalcutpro plist/preferences/caches.
Copy pasting in new timeline ( prores or native) also helps a lot indeed.

[Paul Jay]

You can change the settings in the Log and Transfer preferences.
Have you matched your FCP timeline?
When you drag your file in a empty timeline , on default, fcp should ask if you want to match the timeline with the fileformat.
Have you done this? If not. Check out your sequence settings.

[Paul Jay]

With an external harddrive you could edit most HD formats on this machine. Far from mediocre.
Indeed. don’t use Proxy. The name says it. It’s a proxy (offline) format.
Use LT or normal ProRes 422

[Paul Jay]

in this case a 10 bit timeline only helps a little when you have a lot of text/graphics etc

[Paul Jay]

Create a new admin user
logout, login with that new user.
Check if it crashes now