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