I'm using the latest nightly, have upgraded to Mac OS 10.5.5, and I've enabled the hidden DX9 routines with Regedit. I'm also using a freshly installed Steam version of HL2. Here's my problem. I launch the game with the -dxlevel command to set it to DX9 mode, then relaunch without the command, as instructed. But anytime I try to alter any of the advanced graphics settings from what they default to (say, to turn VSYNC on) the game defaults back to a lower DX level, either 8.1 or 7.0. I then have to resent it to 9 again, and the whole process starts over again. So I cannot seem to run the game in DX9 and make any changes to the advanced settings.