installing not allowed: permission problems

[27 houdini's]

photshop 7.0.1 was getting buggy, so i ditched it and tried a reinstall. but somewhere near the end i get the message that i cannot install because i do not have the privileges! I am the administrator and have all privileges

Anyone got a clue?

 

[Zammy-Sam]

did you try repairing permissions before the installation?