I have a situation where my computer when switched on would go straight to my XP Desktop screen then yestday for no reason it now asks me to log in with a oblong box in the middle of the screen and asks me to log in, I have tried to delete any other "users" ( there are none just me using the computer) but this hasnt helped and when I log off it also comes up with the ams sort of box rather than just switching off
I am not really computer smart so I would apreicate any help or advice, thaks Bruce

Control Panel > User Accounts > Change the way users log on or off:

Uncheck > Use the Welcome screen