I had installed Counterspy, but it interfered with regular operation of the computer, so I deinstalled it. i have since discovered that it has left behind a registry key...

HKCU\Software\Sunbelt Software\Counterspy\Alerts

which has about 613,000 subkeys! This really clogs my system, makes booting up and turning off take forever. I can only even display the subkeys with Registry Explorer 1.4. Regedit and Regedt32 choked and hanged during display. And Registry Explorer will only let me delete the subkeys one at a time.

CCleaner was suggested, but it doesn't even find a problem. It doesn't see Counterspy as a program to uninstall, and it doesn't see any registry problems.

I would be grateful for any ideas short of reinstall of XP Pro SP2.

welcome to the CC forums
what you could do is create another user account.
this has its own set of registry keys and it would not include counterspys.
try it and let me know what you think, it doesnt take that long to move all your information from one account to another
-aaron

Well you could just make a .reg file to delete those for you.

Enter this in notepad and save it as DeleteAlerts.reg

Then just merge it into the registry and regedit *should* just automaticaly delete it.

good idea, just save that as anything.reg and you should be set.
just be sure you dont need those keys anymore!
i would set a restore point just incase, start>programs>accessories>(system tools)>system restore

Ya, we don't want to cause any more problems for you!