I cannot install my graphic/photo software

Hi All,
I got a problem with one of my photo/graphic software. Whenever I try to install it, it will stop in the middle of the installation and would say that My system has not been modified, which means that my installation is incomplete.
It is asking me to run the setup again and I do not understand why it says that I do not have the privileges to do the installation. I made my account the administrator of the PC.
I will really need to use this software, but the installation will not be completed. I hope someone will be able to guide me with this as well as the best and easiest way to resolve this issue.
I have been trying to resolve this for a month now, and I am not able to see the resolution in the net. So, if someone was able to encounter the same issue and was able to surpass it, please let me know the solution so I can resolve mine as well.
I am using an HP machine running on Windows XP.
Any help will be appreciated.
