Half-Life 2 loading problem

[Bahs]

Hi there!

I began playing HL2 about a week ago. At first I had some problems with A.I. Disable, but I got it fixed and continued playing. But then a few days ago a new problem showed up: Whenever I want to load a saved game and it get to the loading screen, it freezes when 75-80% of the loading-bar is full. - Allways in the same place. This also happens if I try to start a new game, so I can't play at all.

I have tried restarting my computer, reinstalled the game, tried running it in a window instead of full screen - nothing helps whatsoever.
So now what do I do?

I got the game from The Orange Box, and all my other games work fine.
My computer is as following:

Laptop from the brand Zepto.
Running Windows Vista Basic 64-bit
4 GB RAM
320 GB harddrive
Intel Core 2 Duo 2.4GHz
NVidia GForce 8600GT

I have no clue on what to do now, so please help me.

//-Malte, Denmark

[Bahs]

Oh yeah, and I HAVE READ AND FOLLOWED THE STEPS.