Half life 2 problem - please help

[spzattk]

Hi, at first I wasn't able to get HL2 working, so I went here and found a way to make it work by going to "set launch options" for the game and putting in "-directX 70" or something like that. It worked for awile, but now it stopped working again.
The game starts fine, but when I load from where I left off the game I get this message:

The instruction at "0x20234939" referenced memory at "0x00000000". The memory could not be "read".

Then I click OK and the game closes.

Does anyone know how to fix this? I'll appreciate any help.

edit: Not sure if this is important, but I have a windows XP and the graphics card is a radeon mobility X1400. I have directx 9.

 

[AciD]

use -dxlevel 90

 

[spzattk]

I got it to work now. I think when it saved there was an error which is why I couldn't load. I just restarted the chapter/level and it worked fine.
Thanks acid, im using dxlevel 90 too.