"Unable to load materialsystem.dll"

[HOppingSQuirrel]

After I've finished downloading Steam and HL2 and I want to start playing the game I get the fellowing error message:
"unable to load materialsystem.dll"

Can anyone help me with this?

Regards,
HOppingSQuirrel

 

[JellyWorld]

Try one of these.

1. Redownload
2. Validate
3. Check the steam forums