Have you installed your retail copy of Psychonauts, or downloaded the PC demo only to have it crash or be generally whiny? You might benefit from the patch which Majesco has made available.
"This should fix some support issues, like more support for Thunderbird CPUs."
There are 11 mb downloads available to patch up either the retail PC version or the PC demo. Get them from the Psychonauts.com Links Page
Also, if you haven't yet downloaded the demo, Majesco is offering a version which is pre-patched, on the "Gray Matter
" portion of their site. You have to register first, but other than that it's less of a hassle.