Focus set issue with IE8 and IE9 on mouse click

Hi,

I have an application created in ASP.NET and integrated in sharepoint using features.
In that app I have an .aspx page having 3-4 textboxes and this page is postback after every 10 sec using timer event.
Also I have used the Updatepanel in my  app.

Now my issue is related to IE8 7 IE9 only not with IE10.(It works fine with IE10)

After postback(panel refresh), when I click on the textbox control  it works fine for first one but after subsequent refresh,
focus goes to the start of textbox,
and I am not able to edit it's content, untill i click somewhere else and back to that text box again.

Note:- App is in .net 4.0.

So will you provide any workaround/Solution for the same?

Thanks,
Vivek