does anyone ever have this happen in apprentice:
You save a file. It says it saves successfully. You open it later on only to find that the file is empty and all of your objects are gone. The file size appears correct as if there's something in the file. This is happening to me quite regularily and it's really annoying because when I save my files i don't have assurance that my data is actually being saved.

I find that of Houdini develops an OpenGL or a redraw glitch, DO NOT SAVE. Just get out of Houdini, restart it and continue. My best understanding is, that Houdini (Win2K version) is do extensively tied into OpenGL, that any problem with it, will corrupt saved projects, even though no error may be issued. I save a lot and save incrementally and do not put all my faith into Backup files that are automatically saved. The backup is saved after user defined saved, and thus is the same file.
Unfourtunatly I find that Houdini is very sensitive to OpenGL issues under Windows. Having Maya and Houdini running concurrently is not good. Those two don't play well together in my system, GeForce3 64mb DDR. So a solid prolevel OpenGL board is a neccessity for Houdini, while it may be a luxury for MAX, Lightwave , or Maya. I was very happy with GeForce3 under Maya, but Houdini, with heavy projects will go bunkers with consumer level boards. For my next system, I have my eye on Matrox Parehlia. For $599 (msrp) you get 256mb ram and 3 screen output.

Dave Rindner

i think i solved this myself.

i put the HOUDINI_COPTOPMAT variable in the wrong spot

Nope. it's still not working. I've narrowed it down to using Materials though. If i use materials, it doesn't save properly.