Sonali Why you want to lock the screen, and yes your thaught is right that when you refresh a grid all the columns gets refreshed but only those column who has other than standard controls like Combo Boxes, that you have to give requery() it.

But Sonali have you checked at what exact times they are getting refreshed and where they are not..

To Solve the Problem it's Must to Isolate it. !!

Regards
Raj