Hi kishore ,
When you record the actions on a yahoo page.
The recorded scripts will contain identifiers which consists of data like, number of read messages etc which are dynamic.
For Eg: an identifier of the inbox button could be "Inbox 297" , where 297 would be the number of mails in inbox to be read. So each time when these values change it will cause problem for QTP to identify them from object repository .
The easiest thing we can do to reuse this code would be to change such identifiers using regular expressions ie, we can change the text identifier "Inbox 297" as "Inbox [1-9]+" in the object repository. Also we can use smart identification for these scenarios.