how to stop open of crm records in new windows ms crm 2011

Hai all,

I want to do the customization which is a bit tricky (I guess).

When ever we open record (Account, contact, etc.,)  in crm 2011, its opening in a new window which is the default functionality of the crm.

But I want it to open in the same page without poping up a new window. How can we acheive this functionality.

Thanks in Advance