Game crash during major scripted scenes?

[Zombotron]

After a defragment/junk cleaning today, I've found that HL2 will crash during scripted scenes, specifically, when I first get to Kleiner's lab.
What's wrong?

 

[xX NoTe 2 SeLf]

every scene is scripted...

 

[Narvi]

Validate your files using Steam.

 

[bbson john]

every scene is scripted...

 

[xX NoTe 2 SeLf]

Ya Rly!

 

[Jintor]

Except for, you know, the fighting.

 

[Acepilotf14]

No Wai!

 

[Beerdude26]

Click on this link to validate your files: steam://validate/220

 

[Zombotron]

It still crashes...
what else could be wrong?
The game was just fine a few days ago....