I have a simple aspx file
<%@ Page Language=\"VB\" AutoEventWireup=\"false\" CodeFile=\"test4.aspx.vb\" Inherits=\"test4\" %>
I know I'm late to the party with this one, but I still wanted to tell my story.
I had a text changed event handler on a read-only TextBox.
JavaScript changed the TextBox to read/write, but the event wouldn't fire. Probably because the back-end still thought it was read-only.
I fixed the issue by moving all changes between R/O and R/W to the back-end. Now it works.