Windows Hangs then Crashes

Windows ME Version 4.90.3000 Build 3000
System Model 15137200060380
System Type X86-based PC
Processor Intel(r) Celeron(tm) GenuineIntel~702Mhz

WHAT HAPPENS IS THIS: the computer sorta like "freezes"
and then, with movement made using the mouse, the system
reboots. This will happen most often when I've left the
computer for a couple of minutes or else when I have a
lot of stuff running at the same time (i.e., cruising the
internet and pages are piling up).

WHAT I'VE DONE TO THIS POOR COMPUTER: first of all, a
long time ago I added some extra RAM cards to the
computer. I didn't have any immediate or noticeable
problems so I tend to rule this out. Secondly, I checked
the config.sys thinking I would change the STACKS TO
9,256 but it was already like that.

However, this struck me as being a bit odd: when I ran a
search to locate the config.sys file, the results list
showed that the config.sys file was located in four
separate folders. Two of these folders had zero KB. All
of these folders had different "modified" dates. Here's a
list of the four folders:

C:\HP\BACKUP ... 0KB
C:\Program Files\Norton SystemWorks\RescueDisk ... 1KB
C:\ ... 0KB
C:\WINDOWS\COMMAND\EBD ... 1KB

The backup file being empty like that made me a little
bit nervous. Any opinions? Would this situation cause the
computer to freeze up and shut off?

OTHER CONSIDERATIONS: I haven't defrag'd the computer in
a long time and I've got a lot of junk on the darn thing:

Total Phys. Memory 62.45 MB
Available Phys. Memory 400.00 KB
Total Virtual Memory 2.00 GB
Available Virtual Memory 1.78 GB
Page File Space 1.94 GB

Thanks for any help that's available out there! I'm not
very good on the computer.