Shouldnt I be getting 404 errors(page not found) for .asp pages that dont exist instead of HTTP/1.1 500 Server Error. Never seen this one before
I have noticed this on two other accounts, while other domains on the same server don’t have this issue at all. I tried many ways to resolve it, permissions, etc and could not find exactly what was making it happen. I know one domain still having this and will give it a shot again to fix.
i have a couple dedicated servers offsite and get the same issue i have been looking into it etc but with no avail. from some parts i have read it could be something to do with app Pools.
my offsite dedicated servers run on Hsphere V3.x , this does seem a little weird i will let you knopw if i find out the issues
I have seen it on 2.4.3 and 3.0 both, and they use quite different pool setups, so I think the problem could lie with the only thing the same, the log engine 
its been the cause of MANy problems to this point.
forgot to mention the servers i have this on is W2K3
As are all ours now 
We have no Windows 2000 in at all.
Finally we found the reason and a very simple solution of this issue.For some reason Hsphere was making some undesirable changes in website configuration in IIS which was causing this problem.We need to revert back this change in IIS on website level to fix this.If this error is happening for you,please submit a ticket and we will resolve the matter.
Turning off custom error messages in my win vps also seemed to fix this issue