Follow these steps even if you already did some of them.
1) Create a directory
C:\hl2server
Make sure it is totally empty.
2) Close steam and any hl/hl2 game you may be running on your pc.
3) Get the hlds update tool.
HldsUpdateTool.exe
Save it to c:\hl2server
4) Open a dos box and go to c:\hl2server
by typing cd \hl2server <enter>
5) Run HldsUpdateTool.exe
It will create another file in c:\hl2server
Now if you want a source server type this in exactly.
HldsUpdateTool.exe -command update -game "Counter-Strike Source" -dir c:\hl2server
It will take a while to dl the almost 1Gig of stuff.
Now start up your server by 2x clicking on c:\hl2server\srcds.exe
You will get the gui startup this way.
If you prefer to have a batch file that will auto restart the server on crash create this .bat file and run it.
title srcds.com Watchdog
:srcds
echo (%time%) srcds started.
start /wait srcds.exe -console -game cstrike -autoupdate +map de_dust +maxplayers 32
echo (%time%) WARNING: srcds closed or crashed, restarting.
goto srcds
I just did those exact steps about 2 hours ago and my source server is running fine....
(This should be a sticky)