cs black screen at start up

hi u guys thanks for viewing

Whenever i start up counter-strike 1.6
it shows the 2 Cts holding their guns, u know when u load up CS it shows the 2 guys and then the menu pops up : find server, friends list ect.

well when that shows up EVERTHING TURNS BLACK everything i get a blank screen, i can only see my mouse. i move the mouse around i can hear the clicks of the menus when i go over them. i than have to alt+tab and click on counter-strike icon at the bottom. when the screen comes back up i get the black screen again.

i have to do this about 14 time until i get the CS screen back. it sucks....

a lot of people have this problem but i have searched the forums and came out empty handed. PLEASE HELP ME!!!