I found the log files and was finally able to get the WAMP stack to run.
The httpd.conf contained the following at the bottom of the file:
PHPIniDir "C:/Bitnami/wampstack-7.0.11-2/php"
SetEnv OPENSSL_CONF "C:\Bitnami\wampstack-7.0.11-2/apache2/conf/openssl.cnf"
SetEnv PATH "C:\Bitnami\wampstack-7.0.11-2/apache2/bin;${PATH}"
Include "conf/deflate.conf"
Include "C:/Bitnami/wampstack-7.0.11-2/apache2/conf/bitnami/bitnami.conf"
Which I changed to the following:
PHPIniDir "C:/Bitnami/wampstack-7.0.11-2/php"
SetEnv OPENSSL_CONF "C:/Bitnami/wampstack-7.0.11-2/apache2/conf/openssl.cnf"
SetEnv PATH "C:/Bitnami/wampstack-7.0.11-2/apache2/bin"
Include "conf/deflate.conf"
Include "C:/Bitnami/wampstack-7.0.11-2/apache2/conf/bitnami/bitnami.conf"
I havnt tested it thoroughly yet, but at least apache starts and I can see the Bitnamie start-page ..