HP ALM 11.50 Service Unavailable (HTTP Error: 503)

We frequently receive Http 503 (service unavailble) error whil accessing HP ALM 11.50. It's getting resolved only after restrating the alm service. Any body face this issue? 

For ALM 11.0, it used to be jboss server and log file can be found at C:\programdata\hp\alm\jboss\server\default\log. As ALM 11.50 uses Jetty web server, please let me know where can I find the log file?

Thanks in advance.

-SHA