I can't reinstall my Guild Wars!!!

I uninstalled Guild Wars one day and then tried to reinstall it later but it didnt install. My computer has all the correct spec.s and it still wont install. Can u guys help!? If it helps this is the message that appears when i try to install it:

Quote From Dialog Box:

"Already Running

Guild Wars is unable to start because another copy is already
running on this computer, or becuase the application has
insufficient rights to successfully detect whether another copy is
already running on this computer."

Press ctrl alt delete and see if there is a gw.exe already running. Close that down if so.

If he uninstalled correctly (plenty of people don't know the correct way to uninstall a program) there should not be an instance of guildwars running. What this message sounds to me like is he's not logged in as administrator and therefor the guildwars install isn't able to check whether guildwars is installed or not.

If this is your parents pc, have them log in and install it.

Whenever I run into similar problems by not being able to reinstall programs, often the solution is cleaning the registry. Sometimes the registry entries are not cleared and the install wizard detects the sofware as still being present.

Get some registry cleaner.