cs wont run???

[bluedishwasher]

i installed counterstrike: source on my pc. currently running winxp pro. the game installs but when i try and run the game nothing happens. I press ctrl+alt+del and it says the games running,,, but i dont see anything on my screen apart from the usual windows desktop any ideas gratly appreciated

 

[bluedishwasher]

now i just get a black screen and nothing happens