Hi Ryan,
Yes, versions of Houdini prior to 5.5.36 (the Apprentice version) are not compatible with XP due to bugs in the Windows code. We had to work around their bugs

Anyways, you can use Windows 2000 or NT (sp6) without problems or wait until 5.5.xx is available to you.
Cheers,
Peter B
Ryan DVS
I've installed houdini 5.046 on win xp with an Nvidia geforce 4 ti4200 with the latest detonator drivers. Houdini constantly crashes and I havent been able to enjoy the new version at all yet. In particular when I try to open oul houdini files -ver 4.035 it just crashes. There are some wierd video things going on as well. The some buttons were re-drawing themselves every time the mouse passed over them. I upgraded from a gf 2mx to avoid these video problems. I have tried disabling smooth line drawing and fiddled around with double-buffering and yet after a certain amount of time the H. still crashes. When did H 5.5 become available? maybe it has the solutions to my problems? -for now I dl the .96 upgrade and will try that. I may try to re-install the program again also. :?