You mentioned that everyone logs on as Administrator (I assume you mean your family)but what's the name of the actual administrator is it you or someone else in your family. You might only have limited permission to change items on the computer. Go to control panel>administrative tools>computer management and click on the plus sign next to Local Users and Groups and the click on the folder Users to see what name is actually under the Administrator. Backup Operators and Power Users have limited access to what they can or cannot add/modify.
I use Windows XP SP2. We only use one login for Xp which is the admin but when I try to download and install programs such as Real Player I get an error message stating that I do not have Admin access. Anyone have a similar problem or a possible fix? I have tried to make a new login that is also an Admin but get the same error message using that. Thanks in advance.