I was running the Microsoft Malware scan from the MS site and went to lunch with the system running. When I came back the system is shut down (power off) and will not power up. Any ideas?

If the computer only turns on for a second, then you are not even getting past the POST (Power On Self Test), and it is not an operating system issue, therefore the MS Malware scan you ran could not have caused it. It may have just been a coincidence that it happened at that time, most likely you are looking at a dead motherboard or a dead power supply.

No problem... sorry its not better news. I would still suggest if you know anyone local that could take a look at it they may be able to come up with something, maybe even a local computer shop, if its really dead they shouldn't charge you to verify that...

The lights come on and the the fan starts, all for about 1 second before it all shuts down again.

Sounds like I have a dead machine. Thanks for the help.

It was in the shop at Best Buy less than a month ago, so I am taking it back to them tomorrow to ask what gives.

The Geek at BB was able to do a lot quite quickly. He removed the battery and the laptop started right away on AC power. I have since run the MS Malware program which found nothing at all and I ran Spybot that found two cookies. I have repaired the software damage that made me suspect a problem in the first place (missing fonts in a word processing program). I'm still not entirely comfortable, but I'll have to see how things develop.

I also have a desktop machine that (unfortunately) I put Winferno on. I have not done too much about that one as yet. I have done a standard uninstall and I ran Spybot that found about half a dozen cookies. I'm not sure what to do next.

What do you know about Winferno? Is it actually a virus? Is it something that we should expect an anti-virus program to detect? My laptop was under McAfee protection the entire time, and the desktop has been under Norton protection the entire time. Both systems update signature files regularly on an automatic basis.

I'd appreciate any advice you have regarding what my next step should be.

As far as i can tell, it does not look like bad software:
http://archive.laptopmag.com/Review/Winferno-Registry-Power-Cleaner.htm
however for registry fixing, i would suggest uninstalling Winferno and running the CCleaner "Issues" scan, which cleans out registry issues very well and has never caused a problem with me.
http://computeradvice.mikebinns.net/removeTempFiles.php (scroll to the bottom for the issues tab instructions)

I thought I responded to this.

The Geek at BB popped the battery out and the laptop started right up. His diagnosis was that a power system spike caused it to trip out a protective device. It seems to be working OK since then. I have completed the MS Malware scan and a Spybot scan. MS found absolutely nothing; Spybot found two cookies. I have removed Winferno with a standard system remove, so we will have to see what happens next. This does not really explain the original problem of the missing fonts, but everything seems to be working OK for the present moment.

Although an error stemming from a scan may have caused the operating system to crash and the computer to turn off, it is highly unlikely that the scan would cause the computer to not power on at all. When you try to turn it on, what happens? do the lights in the front of the computer that normally turn on do so?

I'd be interested to know what it turns out to be, post it here when you find out.