I'm running Sorenson Squeeze Compression Suite 4.5.6 on Windows XP (Dell Optiplex GX620) and I've noticed that it continually craps out on me if I batch any more than, say, ten videos at a time. Or fewer if the source size is anything bigger than 40MB.
My source files are typically QuickTimes or mpegs.
I've had this problem too. Ever since I upgraded to 4.5.6 on my Mac, Sorenson has been spontaneously closing. I'm going to do some research to try to figure out what I can do, because it is quite annoying.