>I believe the bottom check boxes are only visible if the "Optimize for performance' radio button is checked. Don't know why that isn't available on your machine (maybe because there's a RAID controller or something else controlling cacheing). IAC, I disabled cacheing on my server and still get the errors.

Yes, this is what I thought as well. We have a RAID solution here and I believe this is relation.

>More bad news - I can get errors on NET1.1 as well as .NET2.0 - in my original test I hadn't jacked the thread count up to the same level....

Thanks, I will update the bug report.