Major HL2 problem

I'm still in the very early stages of the game. I exited out once, but when I came back into the game a message on the screen said "ai disabled" this is very annoying. Is there any way to fix this?

Are you running a 64-bit version of Windows? This is a known issue on 64-bit Vista and possibly other x64 versions of Windows as well. HL2 automatically runs in 64-bit mode when on a 64-bit OS, and all seems to go well the first time. But every subsequent run will show that message when you start playing again, and NPCs don't move. I think you can "almost" fix it by putting some tweaks into the game's autoexec.cfg, but it's not perfect.

I don't remember all the details but I do remember that I tried everything, and never found a 100% perfect solution.

I opted to run the game in 32-bit mode, which works flawlessly. To do so I added -32bit to the game's Launch Options in Steam. This isn't necessary for HL2 Ep1 and Ep2, as those don't have 64-bit mode and only run in 32-bit.

Edit - I forgot to mention: Your game 64-bit game saves won't be available when you run the game in 32-bit mode, and Vice Versa.

holy crap dude. thats... crazy. wish i could help. best of luck to you.

very easy solution to this, i had the same problem

just do the following: right click the half life 2 icon in your steam games list, then go to properties, then go to set launch options, then type in "-32bit" (do not include the quotes but DO include the - sign)

I have 64 bit windows and this is what I did

Go into your hl2cfg folder, and create a txt file, inside this text file, write the following lines.
ai_norebuildgraph "1"
ai_disable "0"

Save, then rename the text file to ai_fix.cfg, right click the file and set it to read only.
Next, open up valve.rc in notepad, you should see the following
// load the base configuration
//exec default.cfg
// Setup custom controller
exec joystick.cfg
// run a user script file if present
exec autoexec.cfg
//
// stuff command line statements
//
stuffcmds
// display the startup level
startupmenu

under "exec autoexec.cfg", add this line
exec ai_fix.cfg

Save the file and your done!

worked for me, best of luck to you =)