New application not available to other users

My iMac is set up with a separate user account for each family member. My wife has admin priveleges, my daughter's is a general account and my son's is restricted (i.e. kid friendly).

I just installed Rosetta Stone v3 from within my account. I confirmed that it runs properly; the installation was successful. My next step was to check that my family could use the program. Within my wife's account I got the following message: Fatal Application Error 5118. Naturally, my first thought was Permissions. I went back to my account and set the group Everyone to have read/write permissions and set the third menu (Others? Guests? I forget what it's called...) to read/write too. Back to my wife's account; Error 5118. I looked in the Get Info window to confirm the changes took place and they had. I restarted the machine, checked Get Info again (still read/write for everyone) and once again got Error 5118.

I've called Rosetta Stone. Of course they're not Mac-saavy, but they indicate Error 5118 is a permissions conflict.

My question(s): is there any way to ensure that applications I install are available to all users? Do I have to log in as Root (something I HATE doing) to install new applications?

Thanks in advance...
Dave