georg,
Well, what a frustrating day it was!!!
After following your excellent, detailed instructions, and after a number of false starts and about 15 reboots some of them prescribed, others due to problems that cropped up as youll see I finally finished my reply to you and clicked on the button to post it, when all of a sudden the MSFN website goes down. As of this writing (Im preparing this in Outlook, to copy and paste when the site finally is up again), Ive been waiting for just about three hours. I suppose its Sunday night site maintenance.
Anyway, I want to express my gratitude for the extensive protocol.

Although I have completely lost my reply to you as Id originally written it, Ill try to reconstruct what I said. Basically I will be quoting your directions, and then providing my results or comments on each as we go along. For convenience, my comments are prefaced with a dash (--) and start in ALL CAPS. So here goes
First, go to Control Panel > Add/Remove Programs > Click the Windows Setup tab. It should load successfully and let you add or remove Windows components. If your system gets screwed up, that's one of the things that often breaks. Works OK?
--YES.
Second, go to Start > Help That's another thing that breaks easily. Works OK? Then exit.
--YES.
Run Sysedit
autoexec.bat should be empty
config.sys should be empty
system.ini should have no lines begining Run=
Exit
--AUTOEXEC.BAT is not empty, but it consists entirely of REM lines.
CONFIG.SYS is not empty, but its mostly REM lines. However, there are three DEVICE lines, for SETVER.EXE, RTC.CLK +R, and HIMEM.SYS. However they might have gotten there (for all I know, theyve always been there), Im not brave enough to remove them.
SYSTEM.INI did not have any lines starting with Run=
Start > Programs > Accessories > System Tools > Scheduled Tasks > Delete any that exist
--DONE. I had scheduled periodical tasks for defragging, ScanDisk, Disk Cleanup, and Norton SystemWorks One-Button Checkup. (None of them at the same time as any of the others.)
Right click My Computer and choose the performance tab. In the middle of the box, it should say:
"Your system is configured for optimal performance."
--YES, thats how it reads.
Under Advanced settings (at the bottom) click the File System button, and the Hard Disk tab:
Typical role of this computer: Network server (no, mine isn't networked & it isn't a server, but if you have more than 16MB of RAM you can choose this setting to increase the size of the file and directory cache.)
--DONE. I had that set to Desktop computer, and therefore changed it.
Read-ahead optimization: Full
--YES.
Click the Troubleshooting tab. None of the boxes should be checked.
--YES.
Back to the Performance box, click the Graphics tab. Hardware acceleration: Full
--YES, thats right.
Click the Virtual Memory tab. Tick "Let me specify my own virtual memory settings)" and then check the box to "Disable virtual memory (Not recommended)" OK, Close, restart. When it comes back up, go back to Virtual Memory and Tick "Let Windows manage my virtual memory settings (Recommended)". OK, Close, Restart. This will flush and defragment your swap file to make certain you are not using one that has become corrupted.
--I HAD a bit of trouble here. After disabling virtual memory and restarting, instead of my usual desktop I saw a Restore Active Desktop screen, where moreover nothing worked except (IIRC) I could move the cursor around uselessly. I ended up having to reboot with a floppy and restoring a previous registry CAB using SCANREG.EXE in DOS. Started the protocol all over again (in case any changes were lost), getting as far as disabling virtual memory, and the same thing happened again.

I think Id better leave the virtual memory alone and let Windows manage it. Ran through the whole protocol (up to this point) once again.
When the system comes back up, right click the desktop and choose Properties.
Background should be: (None)
Screen Saver should be: (None)
Effects: No boxes checked.
Web: No boxes checked.
Settings: 800 x 600, True Color (24 bit)
--DONE. The monitor settings did include a True Color choice, but it was 32-bit and not 24. There was, among others, also a 16-bit High Color option. I selected the 32-bit True Color.
Double click My Computer and right click Drive C: 30% or more free space.
On the Tools tab: "You last checked this drive for errors 0 days ago"
--HDD space is ~6GB out of 12. It claims that I last checked the drive 135 days ago, but that must be because I had to resort to the backup registry with previous information. I last did a whole ScanDisk run just last week. ADDITION: Did a new ScanDisk and Defrag overnight while waiting for the site to come back up.
Run msconfig. Nothing should be checked except System Tray.
--DONE.
Load Spybot Search & Destroy. Set to Advanced Mode.
Tools > Resident > Check "SDHelper" but leave "TeaTimer" unchecked.
Tools > System Startup > Nothing checked but SysTray.exe and Explorer.exe
Settings > File Sets > Uncheck all indented file sets, leaving only the topmost box checked.
Settings (at the top) click the Defaults button.
--ALL DONE.
At this point you should have no running programs except SSD and no icons in the System Tray.
--YES. It does still show the Volume icon for the speakers.
Click Search & Destroy and then Check for problems.
--DONE.
The status bar should read Running bot-check (29/29...
On this run I got a green check mark in one minute 37 seconds. You?
--UH-OH: Spybot ran through the entire progress bar in a fraction of a second and then the whole screen froze, even the cursor. So bad that I had to turn off the power. Tried it again, first going through the entire protocol again to make sure that no settings had gotten messed up or reverted to the previous value: same thing happened. SSD never did get as far as showing XX/XX, or even an error message of any kind when it crashed.
It was at this point that I finished composing my reply to you (Id been adding items as I went along), then hit the button to post it and the MSFN page became unavailable. Internet Explorer cannot display the webpage is the exact phrase Im getting. (Other websites are working just fine, except for strangely enough the Win98banter.com forum.)
Subsequently, as a test, I rebooted the PC, reloaded Spybot, and added some of the file sets back in, just to see what happened in this reduced memory load environment. It ran through the scan as before… and as before, it gave me the blasted illegal operation/invalid page fault message at the very end. AAARRRGGGGHHHHH!!!
End of reply. A long and frustrating day. Now Im just waiting for MSFN to come back up so I can post the reply. And running ScanDisk again, in case thats needed in order to proceed properly from here on out.
So Doc, what do you think?
--JorgeA
This post has been edited by JorgeA: 19 April 2010 - 09:26 AM