There's 2 or is it 3 types of logon that xp orignally came with ,the icon type for quick logon & no password,the icon type but need password,then there's the one that has a little rectangular box that requires user name & password you select the one you want under accounts i think ?? the test thing you mention is odd i have an S5020AN Presario 2004,i have never seen any option for a test screen logon & believe me if it were in here i would've found it,is there in your programs list any sort of wording along the lines of,system fault finding,system help,troubleshooting, i think your logon issue is due to some either new hp software for trouble shooting from the program list or new software that has been installed or a logon created by the repairer so he/she new which account they were in,other than what i've written below i'm pretty much lost as to what to suggest short of using the repair windows function,why can't you just get hold of the repairer it'll save a stack of speculation
A longshot that most probably won't work: would creating another admin user account then deleting the one your having trouble with work ?? you'll be give'n an option to save the old account in a folder inside the new account or permanently delete as i remember