Hello Carlin,
Browse to the GDT program directory. That's usually here:
C:/Program Files/Renegade Minds/Guitar and Drum Trainer v4/
On the GDT4.exe.config file, right-click and choose Properties > Security. (You may need to repeat this for the GDTTips.xml file as well.)
Select your username, then make sure that it has "Full Control" permissions. That shoud fix things.
Please let me know how that goes for you.
Regards,
Ryan