In Windows 2000/XP Operating Systems, Microsoft first introduced Policies and
Security Restrictions to Users. This has to do with how the Operating System
treats User Accounts. Depending on how the Operating System was setup when
first installed, Limited users may or may not be allowed to install programs
or drivers or make any modifications to the System.
In this case, in order to perform these tasks, you would need to be logged-on
as a User who has Administrative privileges / permissions as suggested below
"Users with limited accounts cannot always install programs. Depending
on the program, a user might need admin privileges to install it. Also
programs designed prior to Windows XP or Windows 2000 might not work
properly with limited accounts. For best results, choose the "computer
admin" account type."
Generally speaking, Administrative rights are needed to install and unlock
Software or Device Drivers. Once it is installed, you can try changing that
Administrator account to a Limited account and see if it will still run.
In order to take advantage of all the features available by a product VTB
highly recommends that you use it when logged on as an Admin.