You know, I would think the exact same thing but I saw what I saw.
The only thing I can think of is that the server had an issue. After all, it is supposed to execute a perl script when it gets a request for it - never deliver the actual script (but it did).
Today, I tried it again. The calendar appears.
So, conclusion? It's not a calendarscript error, it's an IIS issue.
Thanks for the reply.