My desktop has several user-accounts. Besides the default ones (Administrator, All Users, Default User and Guest) I also have All Users.WINDOWS and Default User.WINDOWS. Furthermore I have Jan Bonte (=my name), Jan Bonte.BBBLAPTOP (BBBLAPTOP is the name of my laptop. I cannot remember creating this user account) and
Jan Bonte.BONTE-01D1E914E which is my current account. I did not make this account myself; I could not think of such a complicated ID. Does anyone know if WINDOWS under specific circumstances ceates user accounts?
Certain programs will create accounts, but they are usually pretty easy to see what they are. Like after installing microsoft's enterprise manager for SQL I now have an account called SQLDebugger with a nice description to go with it. Also, these accounts are restricted to which directories they can access.
If these are all administrator accounts, I think I'd start disabling them and see if it effects any of your programs. Also, run a full virus scan and if you have a malware scanner, run it too.