Everytime when i click on the button, it gives a black screen refresh?

Just wondering it is just the problem about my browsers or anything to solve it?

I dun want it that can be told its refreshing the page.

Anybody know why? thanks very very much

 <asp:LinkButton ID="LinkButton1" runat="server">LinkButton</asp:LinkButton>

<div>
<ajaxToolkit:CollapsiblePanelExtender ID="cpe" runat="Server"
TargetControlID="Panel1"
CollapsedSize="0"
ExpandedSize="300"
Collapsed="True"
ExpandControlID="LinkButton1"
CollapseControlID="LinkButton1"
AutoCollapse="False"
AutoExpand="False"
ScrollContents="True"
TextLabelID="Label1"
CollapsedText="Show Details..."
ExpandedText="Hide Details"
ExpandDirection="Vertical" />
<asp:Panel ID="Panel1" runat="server">
this <br />
is <br />
blah <br />
</asp:Panel>
</div>