JRE_HOME variable missing with Tomcat (win7)

Question

I installed tomcat and Apache http-servers like two weeks ago. I got it running and I was able to run the JSP-pages from another computers. I had a little pause and now that

Answer 1

So, I installed Apache Tomcat/7.0.30 and now the startup runs perfectly. No more 503 error and I can run the JSP stuff from other machines as I should be.

Problem is solved, but the mystery remains. It seems that jdk had nothing to do with the problem. Did my tomcat die of old age or something?