problem with "cmd" and "regedit"

I've just recently discovered a problem with my computer. If I go to start, run, and type in "regedit" a command prompt will appear and lock up. When I try to close it, I get a "Program Not Responding" message and I have to click "End Now." But what is stranger is that, at first, when I typed in "cmd" or "cmd.exe" or "command" the box would simply flash once on the screen and go away. If I went to start, all programs, accessories, command prompt, I would get a command prompt, but if I typed in "ping" and any address, I got a very strange nonsense message:
"EXIST filename Specifies a true condition if filename"
After running several anti-malware programs and restarting the computer a couple of times, now I get a new message in a separate box along with the command prompt every time I type in "cmd" or "regedit" or click on "Command Promt":
(Title bar): 16 bit MS-DOS Subsystem
(Text): C:\WINDOWS\System32\regedit.com (or "cmd.com")
The NTVDM CPU has encountered an illegal instruction.
CS:055c IP:00b7 OP:65 63 69 66 79 Choose 'Close' to terminate the application.
Clicking on "Ignore" changes nothing. I am forced to click on "Close". I am running Windows XP. Does anyone know whats going on. Before I ran the anti-malware programs I could at least run other commands without problems, such as "ipconfig". But now I can't do anything.

 

chcp.com - 8 kb (none)
cmd.com - 1 kb (.exe - 367 kb)
command.com - 50 kb (none)
diskcomp.com - 9 kb (none)
diskcopy.com - 7 kb (none)
edit.com - 69 kb (none)
format.com - 25 kb (none)
graftabl.com - 26 kb (none)
graphics.com - 20 kb (none)
kb16.com - 15 kb (none)
loadfix.com - 2 kb (none)
mode.com - 19 kb (none)
more.com - 16 kb (none)
netstat.com - 1 kb (.exe - 30 kb)
ping.com - 1 kb (.exe - 15 kb)
regedit.com - 1 kb (none)
taskkill.com - 1 kb (.exe - 71 kb)
tasklist.com - 1 kb (.exe - 71 kb)
tracert.com - 1 kb (.exe - 10 kb)
tree.com - 11 kb (none)
win.com - 18 kb (none)

Also, "ping6.exe - 33 kb" and "regedt32.exe - 4 kb". "none" means no matching .exe file.

"But now I can't do anything" means that I can't use the command prompt at all due to the error message mentioned before.

 

Almost done. I just have one more question. When I searched for "regedit" I recieved some results that I found questionable:

regedit.com - C:\RECYCLER\S-1-5-21-1957994488-1644491937-839522115-1003
regedit.com - C:\RECYCLER\S-1-5-21-1957994488-1644491937-839522115-1004
regedit.com - C:\RECYCLER\S-1-5-21-1957994488-1644491937-839522115-1006
regedit.com - C:\RECYCLER\S-1-5-21-1957994488-1644491937-839522115-500

Tje same results also showed up on another drive. Is this normal, or should I delete it?

 

I also seem to have two different regedit.exe. One is 131 kb and the other is 143 kb. The 143 kb is located at C:\WINDOWS\SoftwareDistribution\Download\6ca7b3a8efd5a9b6f87fff395a2eb989.

The other is located at C:\WINDOWS and C:\WINDOWS\system32\dllcache.

Any idea which one I should use?

 

I bought this computer with SP1. For some reason, I have never been able to install SP2. I don't want to think it, but I've been told by my friends that my version of Windows XP may be a copy. I have been able to update on most everything else at the Microsoft site, though.

It would really suck to find out that, after spending all kinds of money, I have a bad OS.

Could this be a part of my problem with the command prompt?

 

The command prompt is working fine now, thanks. What causes this? Should I worry about it happening again if I restart my computer?