Hi,
I am not sure if this will work, because I have no IIE 5.1
Just try:
In your master page code behind:
protected void Page_PreRender(object sender, EventArgs e)
{
HtmlMeta metatag = new HtmlMeta();
metatag.Attributes.Add("http-equiv", "X-UA-Compatible");
metatag.Attributes.Add("content", "ID=EmulateIE5");
metatag.Attributes.Add("content", "ID=EmulateIE7");
Page.Header.Controls.AddAt(0, metatag);
}
Please do not forget to vote if helps, so that others may consider as answer...
Regards,