The Counter-Strike website has been updated with some help for those of you having authentication problems with the master servers as well as word on what that TrackerUI.dll error is and how to make it possible to bind the F1 and F2 keys again to stuff that you want to bind (Thanks Blues)

1) Clients need to communicate with the Secure Master servers (port 27012). First, make sure there isn't a firewall problem.
2) Make sure you do NOT have a file called "woncomm.lst" in your \cstrike folder. If you do, delete it. This file should ONLY reside in your \valve folder.
3) Open the "woncomm.lst" file in your \valve folder (using notepad) and make sure there is an entry that looks like this at the bottom of the file:
Secure
{
half-life.speakeasy-nyc.hlauth.net:27012
half-life.speakeasy-sea.hlauth.net:27012
half-life.speakeasy-chi.hlauth.net:27012
}

You can download the latest Counter-Strike v1.5 updates from Fileshack courtesy of Speakeasy.