Hmmm... After you ran the 4.51 beta, did the program automatically run the patch on the Cows? Apparently, what Vue Pro does in an update is place a seperate .exe file in the main Vue folder, and when it detects that HyperVue is active, should automatically run the Cow version of the patch on each detected Cow. If it didn't, you will bomb every time, as it apparently does a version check to ensure compatibility. You can copy that Rendercow Update onto a CD or across the network manually and run the updater on each renderbox that way (and as this is a beta, I'm assuming that you are running the 4.1 official release first on everything. I don't know if these are cumulative patches or last one has all fixes, but I'd assume the former, just for safety's sake). I'd also get in the habit of saving each upgrade updater for the Cows in a seperate folder, just so you don't have to futz with the full patches anytime the rendergarden units get flakey. If Vue itself is running stable, then I would try uninstalling the ProCows completely, including digging out every trace of them in the registry, run something like Norton WinDoctor, to make sure there isn't something else in the system that is causing trouble (Vue Pro has a -lot- more connections to the OS than Vue does). Reinstall the Cow from the CD, then run each successive patch manually. Ah. Another idea. Do you have PaintShop Pro 8? PSP 8 has its own Python engine and setup, and I found that installing Vue and the Cows over PSP 8 -sometimes- does flakey things to the python runtimes. I had to uninstall PSP 8, clean up the registry, and reinstall it -after- I had Vue Pro and Cows in place. That was just from the release install, and I can't reproduce it consistently by any means, but an unstable Python environment =will= crash the Cows, usually when it starts texture loading, and occasionally will take VuePro down with it. Of course the Benelli 9mm, 36" baseball bat, and the array of computer tools I keep lying about in plain sight of my computers may have something to do with it, too.... ;P