Question : Blue screen of death: 0167:BFF9DFFF

I have a Dell Optiplex GX1 running Win98Se.  This is a refurbished PII running a PIII 800 Mhz CPU.  I am only running 4 programs on it, ECS (home automation software), ACE (additional HA software), MS Personal Web Server (from the Win 98SE CD) and RTV Recox (a small utility that "pushes" buttons for me).  The problem is that virtually everytime I exit the Ace program I get a blue screen with the mishap happening at 0167:BFF9DFFF.  Other details:

I just got this machine and all programs have been freshly loaded.
The author of Ace has been helpful in troubleshooting, it is stumped.
I have tried not loading particular elements (like PWS) but this does not seem to help.
Ace uses VB files
I have a Zoom 14.4 modem installed, ATI 3d Rage Pro video card, Integrated 3 com NIC and integrated Crystal audio.
Have fully uninstalled Ace (more than once) and reinstalled.
Intel 440BX chipset
It does not matter how I shut down Ace, I almost always crash. If I just shut down Windows (with Ace running), shut down via the menu, shut down via Ctrl-Alt-Del (to end task), all crash.
My only recovery is to reset or power down.

Answer : Blue screen of death: 0167:BFF9DFFF

What type of error is it?  Fatal Exception 0E?  Windows Protection fault?  This info is usually very helpful in tracking down the problem.  

Otherwise, have you tried running the System File Checker to see if any system files are missing or corrupted?  You can run it by typing SFC in the Run dialog box off the Start Menu. Have your Windows installation CD ready to replace any missing/corrupted files.  If you don't have a Windows installation CD, then search to see if the Win98 .CAB files are saved somewhere on the hard drive, for example usually in Windows\Options\Cabs.