The problem above was the configuration on an invalid hostname in the network driver section in the used configuration file (i.e. it was not the hostname provided via URL).
Background: newer versions of OpenACS provide a protection against invalid host header files to protect against HTTP host header attacks. In this process, it checks among many other things, whether the provided content of the host header field is actually one of many possible IP addresses of the hostname provided in the network driver section. In case, this name resolution failed, a runtime exception was generated (what was called "complete crash" above).
One can certainly argue, how to deal with such erroneous configurations, but probably in some testing setups, this can easily happen. The updated code in the OpenACS repository writes now an error message to the error log and skips this single validation step.
As, always, the proper place for such messages is the OpenACS bug tracker.
