Help! Really wierd graphics problem

[SYcle]

Hi, I have this really wierd graphics problem, when I try start hl2 it gets all wierd with white boxes and stuff, and this error in the consol
"shader shaders\vsh\LightmappedGeneric_vs11.vcs is the wrong version
Couldn't load vertex shader LightmappedGeneric_vs11"

Anyone have a solution? Thanks
Here are some screens :

 

[Barney_Calhoun]

On my Geforce 4 MX440 it did a similar problem to that on CS:S, but it was ok if I just restarted the game. What GFX card do you have btw?

 

[GonzoBabbleshit]

Verify your Steam files?

 

[SYcle]

I have a RADEON 9200 DDR x86/SSE, and how do I verify my steam files?..

 

[giant384]

http://steampowered.custhelp.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=282&p_created=1101182584&p_sid=I5oz2QHh&p_lva=&p_sp=cF9zcmNoPSZwX3NvcnRfYnk9JnBfZ3JpZHNvcnQ9JnBfcm93X2NudD0yNjgmcF9wcm9kcz0mcF9jYXRzPSZwX3B2PSZwX2N2PSZwX3BhZ2U9MQ**&p_li=&p_topview=1 click on hl2