That error message in the topic title keeps appearing when I start Halo Custom Edition. It used to work fine a few months ago, even with Open Sauce. Now when I start it up, it gives me this.

I have tried:
1. Disabling antivirus and EMET's memory protections and starting up Halo.
3. Ensuring no Halo-related processes are running (that includes Sapien / Guerrila / Tool and OS equivalents)
2. Closing Xfire / Pidgin / browsers and other non-essential programs
2. Starting Halo when Windows has been started in Selective Startup mode (no startup programs save the necessary graphics software like CCC and Virtu).
3. Tried starting Halo in safe mode (both the Halo "safemode" and Windows' safe mode: same error pops up in the former, the latter causes Halo to fail starting due to DirectX being unavailable.)
4. Reinstalling Halo Custom Edition.

My specs are:
Win 7 x64
avast! AV
EMET

Specs were the same when Halo still worked fine, help greatly appreciated.

remove avast, it seems avast conflicts with hce after avast updated from v5.0 or 6.0
it was 1 of them 2 which was the start of the conflict.

hmm... i have avast and halo (both combat evolved and custom edition, also HEK works fine) works fine.
try to run halo ce as administrator and make sure that halo ce root dir does NOT have read only attribute.
Edited by afD2345 on Jun 19, 2012 at 12:43 PM

Is this why my pc randomly freezes?

UPDATE:
I found a way to "solve" my problem, albeit in a very odd way. It involves Xfire and Open Sauce enabled Halo CE.
You know when Opensauce Halo CE tells you to close down Xfire if you have it running before Halo CE starts? I did just that when the pop-up appeared, and Halo CE (somehow) loaded properly.
There were a few caveats though, mainly being my graphics card being detected as "Intel 64 MB", and my ATI driver crashing about a minute after Halo CE started (it restarted, and the crash didn't really affect Halo CE apart from a momentary freeze and Halo CE minimising so I had to put it back to fullscreen).

So yeah, to put things clearly, I did this according to the following steps:
1. Start Xfire.
2. Start Opensauce Halo CE
3. When Halo CE gives you the Close Xfire prompt, close and exit Xfire.
4. Halo CE starts (almost) perfectly.

And no, I did not have Xfire running when I did my original troubleshooting steps in the OP, which makes this very odd indeed.

My current theory is that either the Radeon HD 7970 drivers/Catalyst Suite (I am running 12.4 as of this post) are conflicting with Halo CE somehow, or this could be a Xfire issue. Still, as per all your suggestions, avast isn't off the hook yet, as I haven't come around to testing if avast is the issue.

i'm honestly not sure, avast is suppose to be pretty fair on resource usage.
i take it task manager is not showing anything hogging?
maybe give system internals a run, it can show processes running which task manager doesn't always show.
@sargejohnson, i had never ran open sauce on this pc, that's how i can personally rule that out.
i think i'll end up removing avg and installing avast just to double check the outcome.

edit: just done some poking around...
i had an old screen shot of my own problem starting hce, with avast installed, the av was at V6.0 at that time.
just tried this...
removed avg, install avast ran hce no problems.
set scheduled scan to kick in and started hce, still no problems.
installed open sauce, avast running, hce starts no problem and still runs fine if i start avast scan just before starting hce.
avast running, xfire running, hce starts no problem, obviously removed d3d9.dll, or hce crys.

so with avast now at 7.0 i see no problems now running hce with it.
what about this new updated version of SAPP is this something you should be looking at?
also how long have you been using EMET?

Edited by ally on Jun 21, 2012 at 04:53 PM

edit: just installed that emet too, i have no problems with all this running with hce.
sapp is the only thing i can't test.
Edited by ally on Jun 21, 2012 at 06:24 PM

@ally:
From what you have tested, I think my problem is with the Catalyst software / graphics drivers now. Since 12.4 is the latest as of now, I guess I would have to wait till 12.5 comes out and I install it to see if the problem is fixed.

Also, I do not have SAPP on my computer used to run Halo CE. I use SAPP for my server PC (which is separate) instead, so it can't be the issue here.

As for EMET, I've had it since last year. Recently upgraded to 3.0, so it could be the problem (I would find that unlikely though, since disabling the memory mitigations EMET provides, which I did during troubleshooting, is equivalent to not having it in the first place).