double and triple check disablehtmlmotd.
open internet explorer and go to a webpage so it connects to the internet
(this actually has a good chance of working because TF2 uses IE to look at pages like this, and it can be blocked/non-functional if you haven't used it ever/in a long time)
make sure u don't have a security script/file which blocks it
EXAMPLE: "Create an empty file in your tf directory named textwindow_temp.html and make it read-only (this prevents the motd from being saved & loaded)"
if none of that works it could be something else related to firewall or your browser settings (most likely Internet Explorer) like maybe cookies
edit: DO NOT create a textwindow lmao. that was an example of how your motd could be blocked!!