Hi Adam,
There appears to be an even simpler solution: replace the double forward slash with a single..
Modify tag.aspx from:
Control ctrl=LoadControl("Tag//"+tabcontrol);
to
Control ctrl=LoadControl("Tag/"+tabcontrol);
This appears to work in Cassini and IIS, online and local, in Firefox and IE.
Why do you have the double forward slash anyway? Do you have it in other code locations?
FredD