Problem creating System Image

I did a clean reinstall of Windows 7 a couple of days ago, and now that it's all updated and tweaked to my liking, I'd like to make a System Image. I have a 1 TB external hard drive that I use for the purpose. The drive has plenty of free space on it (over 500 GB). I have been making System Images for years with this arrangement, and have never encountered the error I encountered today:



I tried it with system protection off for the external drive, as I've done for years. I also tried it with system protection on, and plenty of space allocated.

Any ideas what might be going on?

TIA...

Did some searching and found that the problem was with the System partition not having enough room on it. I put the boot stuff on C: and got rid of the System partition - problem solved.

This also explains why I didn't have problems before: I never had a System partition, because I had always installed into a prepared formatted partition, and didn't let Windows set it up the way it wanted.