Getting An Accessible Hidden Account?

Mom bought a Win 7 puter so that my 15 year old grandson, who lives with them, could use it for school work, and play games. She uses it a little to email, IM, and play card games. Mom and dad are in their 70s and don't know anything about puters. They barely know how to use a remote control on a cable box. My grandson began downloading games that install BHOs, toolbars, plugins, etc that slow the machine down till it hangs frequently. I took it, created an admin account, cleaned off a billion toolbars, BHOs and unwanted games, and their tracking cookies, some Trojans, and viruses, and the machine began to respond again, but as soon as he gets hold of it, he accesses the User's Control Panel and lowers my privileges, so that I can't function as an administrator on mom's puter. This upsets the rest of us. He says he has to have admin privileges to install and play his games, and, that I keep messing up his stuff.

I've tried creating an admin account and hiding it from the logon screen, and the User's Control Panel, but that also makes it so I can't logon, not even in safe mode. Seems MS made Win 7 so that if there is just one admin account activated it sees no need for any other admin accounts to display in Safe Mode. I tried the following, "Hide the Admin Account" hack, but Win 7 would not allow me to logon, since I found no way to activate a logon run dialog, nor could I use Safe Mode, cause with His admin account visible, my admin account isn't, not even in Safe Mode.I noticed a thread entitled: Hidden Administrator Account? on this forum, which led me to ask you about this. I'm a "slightly" above average user, so be gentle.I need something hidden from him, even in the User's Control Panel, so that I can maintain this puter and put a stop to his ability to lower my privileges. Any suggestions, other than lowered privileges?Instructions to Hide the Admin Account from the Default Login Screen:You can hide accounts the same way you did in XP, but in Vista and Win 7 you need to create those registry keys.

1.In regedit, navigate to: HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogon.

2.Right click Winlogon and select New / Key.

3.Name the new key SpecialAccounts (case sensitive).

4.Right click The SpecialAccounts key and select New Key again.

5.Name the key UserList.

6.Click the UserList key and in the right side window right click and select New / DWord (32bit) Value.

7.Name the new DWord value with the same name as the account you wish to hide. Double click this value and in the Value Data line enter 0 (zero) to hide the account or 1 to show the account.