We have a new problem-free SharePoint installation running for days. Yesterday I configured the User Profile Service Application. As soon as I set up My Sites, the main web site started giving 500 Internal Server error. I tried to solve the problem for hours but couldn't find anything because there was not a single error entry in Event Viewer and ULS logs. I deleted the web application from IIS, and recreated with the existing content database and site came back again.
After this serious problem, I created a new web application to host my sites, changed the my sites configuration to point to this new application and suddenly the new web application started to give 500 internal error. No error entries in event viewer and logs again so I can't even do any troubleshooting.
Any help is greatly appreciated.