Junk Values in Modalpopupextender

I have a form where i have 6 tabcontainers. Each tabcontainer has textbox and gridview. Everything is working fine. But in 4th tabcontainer i am using modalpopup extender. I have 6 linkbuttons in tabcontainer 4, which pop

up's 6 modalextenders. The problem is whenever i enter some values in textboxes of tabcontainers other than tabcontainer 4(which has modalpopup) junk values(commas[,]) are inserted in textboxes of tabcontainer 4.And popup fires suddendly on some events of other tabcontainers. I wonder modalpopup is in tabcontainer 4 and how it is fired from other tabcontainers. Everything is inside update panel. I doubt desing of modalpopup is overlapping other tabcontainers, could  not make out beacause its invisible. Please solve my problem..Below is the code.

....have some textobxes gridview

....have some textobxes gridview

....have some textobxes gridview

.....

  TabIndex="4">

   Water

     PopupControlID="div1"  BackgroundCssClass="popUpIndustryStyle" cancelcontrolid="CancelButton" x="250" Y="50" >

.....have modalpopup foreach linkbutton

......