Using admin software with user rights

Hi,

I have a problem with this workstation (DELL Precision) with Windows XP Pro.
All software (CAD, 3D) and printers have been installed using the admin user. All normal users were able to use theese programs/printers until we changed the way users log in the computer from normal to “using the welcome screen” mode.
Now normal users can’t use admin’s software/printers. When they try to open a program it takes forever to execute (if it does), and printers don’t print at all. Funny thing is that there are no error/warning messages at all.

Does anyone have any idea of what’s going on?

Thanks