error messages in MWS log

Hi All,
I am getting error messages in my log file
2012-08-09 16:24:45 GMT+05:30 (Framework:INFO) - Validate::handle() - failed to login

This error message comes when I navigate to a specific portlet in my application and these messages keep on populating.
It takes a lot of time to open that portlet and my application becomes very slow.
Any help on this appreciated.