Hi Gemini4 and thanks for the comments.
I could agree with you on the multiple anti-spyware programs IF they were RESIDENT, but mine are not...just executed manually or on a timer once every day or so. Many people recommend multiple programs since no program (that I have encountered) is able to "catch" all spyware. I've proved this again and again by serially running AdAware and Spybot. One will catch some and the other will catch more.
I have not had a "blue screen" episode, so maybe no hardware or driver problem, BUT see below.
The problem occurred yesterday, so I disabled ZoneAlarm Security Suite, but had no effect on the problem. Also there are no Security events logged.
Your suggestion to analyze the System Event log turned up the following error events:
"The driver detected a controller error on \Device\CdRom0." occurred once. Event says "source = cdrom". NOTE I was not using the CD-ROM or CD-RW.
"The device, \Device\Ide\IdePort1, is not ready for access yet." occurred many, many times. Event says "source = atapi"
The only atapi hardware I have is 2 hard drives and the below mentioned 2 CD drives.
How would you decifer these messages?

These occurrences, to be best of my analysis, occurred during the problem, but I cannot emphatically state that. As for CD-ROM (Samsung), I have one and I also have a CD-RW (TDK), both atapi.
Well 5 antispyware programs are not a good ideea. You need just one good one plus your antivirus and firewall.
Now regarding the problem. If you have a hardware failure or driver failure you usually get a blue screen. This looks like something to do with your security software. Just temporarily disable or uninstall it when the problem occurs to see if that's it.
To rule out any possible drivers issues take a look in your event log and let's see if you see any system errors there.