Not responding is a Windows message, not PR. It simply means you have background services / processes that steal sufficient CPU cyles or resources that Windows thinks the program is not responding. Clean up on those processes and services or increase hardware resources to get rid of the problem.
BTW: what do you mean by 'all SATA...'? Is that 1, 2, 8 or what number and how is it configured?
Since you worked 20+ hours, and without any more information, one thing you can do, if you haven't already, is to defragment your drives, especially the drive that contains your video. Working on a video for 20+ hours without defragmentation could possibly cause the problems you are experiencing. Then again, it might be something else. Just a thought.
Premiere Pro only reads the video it uses in projects. You can use it for 2000 hours and the fragmentation of the drive won't change because of it.
Fragmentation happens when you write to a drive, not when you read from it.
I meant that all my hard drives are connecting via the main board SATA ports, no external USB 2.0 connection or anything like that. Specifically the 1 TB drive that the project lives on is mounted into the system via a SATA swap tray, instead of being hard-mounted inside the PC... but I'm assuming that is not an issue. Also the drive is pretty new and does not need to be defragged.
As far as not having enough system resources, that's not an issue; at most the only things I have going on are Premiere, Firefox and an explorer window:
The problem is isolated in Premiere, and nothing else if affected in the system while it's happening; in fact, I've made a habit of checking my email or something to pass the time whilst Premiere stalls on a render or save.
Like I said, the only problem I could see is that there's too many items in my Project Bin and that's causing the issue; there are 909 items there. I'm still getting used to this HD workflow so I just imported all of the footage we shot, making the "edit ratio" something like 72:1. So I guess I won't find out if that's causing the problem until I'm done the edit and can trim out all the footage I didn't use.
Are any of your drives full?
Are you using Mercury Playback Hardware Accelleration? ( seems like you shouldn't have much rendering to do ).
One thing to try is importing this project into a brand new project.
I wonder if there is a problem at all. That Premiere isn't responding to Windows messages during the process of saving your project might be because it is actually quite busy saving your project. Not the best behaviour, perhaps, still - it does save it in the tend, doesnt it? Without crashing? If so, you might want to save a copy of your project to another hard drive and give it another try using the copy. Or, if you are sure you've imported anything you need, try to use the project manager to create a new copy of your project and it's source files. If there was any overhead from interpreting the xdcam-files you attached using the mediabrowser, it should get rid of that as well.
On the other hand, you might have a problem :)
Whatever: good luck
Unfortunately you have used Task Manager, instead of the much more informative Process Explorer.
However even though the Task Manager gives only limited information, one can see you have several unneeded processes running, which can be disabled at startup or killed for the session.
You can kill Firefox and the plug-in extensions, QT server (if you don't use Quircktime), jusched, IAStorIcon and possibbly Microsoft Security. That will remove quite some overhead from the system. A 4% CPU load at idle is excessive.