If anyone is interested I found a work around.
I moved the updatepanel to encapsulate the entire RadGrid (the Timer also is still contained in the updatepanel)
I changed the C# code behind of Timer1_Tick to
foreach (GridDataItem item in RadGrid1.Items)
{
DateTime starttime = DateTime.ParseExact((item.FindControl("Strat_TimeLabel") as Label).Text, "H:mm:ss", System.Globalization.CultureInfo.CurrentCulture);
DateTime nowtime = System.DateTime.Now;
TimeSpan ts = new TimeSpan();
ts = starttime - nowtime;
System.Web.UI.Timer).Parent.Parent.Parent.Parent as GridDataItem;
if (ts.Seconds >= 0 && ts.Minutes > 0)
{
DateTime d = new DateTime(2000, 01, 01, ts.Hours, ts.Minutes, ts.Seconds);
(item.FindControl("lbltime") as Label).Text = d.ToString("H:mm:ss");
}
else
{
(item.FindControl("lbltime") as Label).Text = "Complete";
}
}
Then for every GridCommand I simply Disabled/Enable the timer
InsertCommand: Timer1.enabled = false;
EditCommand: Timer1.enabled = false;
UpdateCommand: Timer1.enabled = True;
CancelCommand: Timer1.enabled = false;
Probably not the most eloquent way as I would have liked to contain the postback event in the Item Template... but it works... Improvements and suggestions are always welcome.