Ajax's update panel provides an easy way of doing this. Just group your radio buttons (those that need to be enabled/disabled) inside one update panel such that (in your .aspx code):
<asp:UpdatePanel ID="GroupUpdateTheseRadioButtons" runat="server" UpdateMode="Always">
<ContentTemplate>
....
<tr>
<td><asp:RadioButton ID="rbtn1" autopostback="false" runat="server" Text="bla bla bla1" GroupName="SendTo" CssClass="radiobtn"/></td>
<td><asp:RadioButton ID="rbtn2" autopostback="false" runat="server" Text="bla bla bla2" GroupName="SendTo" CssClass="radiobtn"/></td>
</tr>
...
</ContentTemplate>
</asp:UpdatePanel>
then your triggering control:
...
<tr>
<td align="left"><asp:RadioButton ID="rbtnTRIGGER" autopostback="true" runat="server" Text="disableEnable" GroupName="TRIGGERGROUP" CssClass="radiobtn" Checked="True" oncheckedchanged="rbtnTRIGGER_CheckedChanged"/></td>
...
Then in your code behind (.aspx.cs)
protected void rbtnTRIGGER_CheckedChanged(object sender, EventArgs e)
{
if (rbtnTRIGGER.Checked)
{
rbtn1.enabled=true;
rbtn2.enabled=true;
}
}
<asp:UpdatePanel ID="GroupUpdateTheseRadioButtons" runat="server" UpdateMode="Always">
<ContentTemplate>
....
<tr>
<td><asp:RadioButton ID="rbtn1" autopostback="false" runat="server" Text="bla bla bla1" GroupName="SendTo" CssClass="radiobtn"/></td>
<td><asp:RadioButton ID="rbtn2" autopostback="false" runat="server" Text="bla bla bla2" GroupName="SendTo" CssClass="radiobtn"/></td>
</tr>
...
</ContentTemplate>
</asp:UpdatePanel>
then your triggering control:
...
<tr>
<td align="left"><asp:RadioButton ID="rbtnTRIGGER" autopostback="true" runat="server" Text="disableEnable" GroupName="TRIGGERGROUP" CssClass="radiobtn" Checked="True" oncheckedchanged="rbtnTRIGGER_CheckedChanged"/></td>
...
Then in your code behind (.aspx.cs)
protected void rbtnTRIGGER_CheckedChanged(object sender, EventArgs e)
{
if (rbtnTRIGGER.Checked)
{
rbtn1.enabled=true;
rbtn2.enabled=true;
}
}