Mysql problem

Hi All,
      I am running a rails apllication where Apache is running frontend
to mongrel. Everything was working fine fews days before but today i
checked my application ,things are not working fine ...i clicked one of
link on one of page in application , am getting below problem

14001: This application has failed to start because the application
configuration is incorrect. Reinstalling the application may fix this
problem. -

am having following installed

ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32]
rails 2.2.2
mysql (2.7.3)

I tried to reinstall the mysql gem as well as per said in error message
but gets the same prblem

Does anyone have any idea why is it so??