Win 7 64 - AMD R9 380
Short description of error
A loaded Text File with Python from GUI Button results in 0 User, and the Textblock ist marked red.
Exact steps for others to reproduce the error
Here is a blend.
Run the Script with Alt+P. It creates a Panel in the scene context of the properties editor.
Place a TXT on the C:\ Drive to load. Load it with the Button. Maybe you need to adjust the Filename in the Script bevore.
See what happens to the loaded Text in the Text Editior.