Got it to work correctly in both user accounts on our Intel mac. I first attempted to change the permissions on them to:
Owner: System, R&W, Group: staff, R&W, R&W, but it still didn't work. Tried to toss the prefs, didn't help. So I removed the Xpert Xtensions, logged in using the root user account - the Main system administrator, not just Administrator. From that account, I reinstalled the Xpert Xtensions, then selected them all and changed the permissions on Access and Others to Read & Write. The extensions now launch in all users with no problems.
I've even had issues in the past with Quark 7 installs where I had to log in through the root user to install Quark 7. I believe that software should be installed this way anyway, but most users do not do this. Many don't even know what a root user is.
I hope this helps someone in need.
Murphy-