How do I correct "can't load profile, file not found" error?

Are you using roaming profiles or local profiles?
Does the folder c:\documents and settings\USERNAME exist?

All my profiles are local. The USERNAME profile exists. However, it is bigger than my available room on my C drive. Perhaps this is my problem.

That's bad, yes. Try to delete all temporary files in this profile.
Relative to your profile, they should be located in "Local Settings\Temp" and try to also clear the temporary internet files.

Oh, sorry, I somehow misread your comment. Having less drive space available shouldn't be a problem. Having no space available will cause troubles of course.

Can you check the permissions of this profile?
After you've logged in, you probably get another profile (a temporary profile) assigned - check that by clicking on "Start" -> "Run" -> "cmd"

Type "set" to see all environment variables and at the bottom of this output you should see the USERPROFILE variable. What is is currently set to?

Can you manually open your not working profile directory in Windows Explorer?

The userprofile variable is set to the right profile (the one it says it can't load)
I can open the directory in the explorer.

I uninstalled Bitdefender which was too big for my 256 meg memory system and the problem cleared up. I think the problem was related to the registry space limit.

Oh, alright. Good to hear that you worked it out.

Your suggestion for looking into the event viewer pointed me to the details of the error which indicated the symptoms in another Experts Exchange response.