Webrick crashes randomy

I am trying Redmine application which is written in ruby. I have set it up on Windows and using mysql database which is remotely located. Every thing works fine except the application crashes randomly and I can't see any error message in logs. But I see a visual studio popup saying unhandelled exception. I am attaching the exception message. Also I have installed Ruby from Windows installer.

*** LOCAL GEMS ***

actionmailer (2.3.5) actionpack (2.3.5) activerecord (2.3.5) activeresource (2.3.5) activesupport (2.3.5) jruby-jars (1.4.0) jruby-rack (0.9.7) mysql (2.8.1) rack (1.0.1) rails (2.3.5) rake (0.8.7) rubyzip (0.9.4) warbler (1.0.1)

Attachments: http://www.ruby-forum.com/attachment/4645/error_message.jpg