One of our CFMX7 servers at work stopped responding a few days ago. All requests would come back with a 500 null error. Looking the logs I found:
I did a quick google search and found this post over at Steven Erat's blog. It mentioned a zero length license file, which is exactly what I had. The only thing is that his post mentions CFMX 6.1, and this was a CFMX7 server. Either way, I replaced the log file and all is better now.