Hi,
I'm currently hosting my forums at Interland and in playing around with some directory settings I had the same problem you had. Interland offers three settings for directories on their NT servers:
1. No scripts, no execute
2. Scripts, no execute
3. Scripts and execute
When the directory was set to number 3 I got the internal server error 500. When set to number 2, scripts only, the scripts executed without a problem.
I believe the execute option is intended for downloading purposes to have a browser trigger the download dialog when a hyperlink references an .exe or .zip in that directory. For the cgi-bin directory this is not necessery.
Hope this helps.
