CZ problem, please help!

[tekkno]

This has been driving me nuts for well over a month. I've googled my butt off trying to find a solution, but no such luck. *edited to remove resolution problem because its not my main concern*
The main problem is on map change or sometimes when i try to join certain maps my game goes to not responding during the verifying/downloading resources screen. i have to ctrl+alt+del and close half-life. I've played all these maps before and I have them installed.
Does anyone know why they would quit working properly or how to fix it. I've completely uninstalled steam/cz from computer, rebooted, deleted maps and manually reinstalled, reinstalled from server download, but then when it tries to load them it freezes.

[MEDIC!!!]

go to your library
right click on the game
select properties
click "Set Launch Options"
and type -startwindowed into the box

[tekkno]

how does windowed mode help with maps making the game freeze? if this is to adress the first problem, i've tried windowed mode, i've tried all the different resolutions and modes. uninstalled, reinstalled, played around with the config file some.switched to my onboard video card and switched back. its been so long i've gotten used to the left handed shooting. i need to know how to keep my game from freezing on certain maps.