This problem was submitted to us by one of our readers who came across a Access Denied error message when opening any .txt file. Sounds strange as text file is one of the simplest files that open up with a notepad, but this is what it is and happens when some changes unknown to you happens in the system.
The reason for the problem is simple and occurs when your txt file associations have changed to some else. I would here suggest a little workaround for the problem. Try opening the Notepad first and then click the File -> Open button and browse for the txt file. If this workaround helps you then the solution listed below will surely help you.
To solve this problem what you need to do is right click on the txt file and change the file association with which it opens. Select Notepad from the options listed in the box and check the box of always open the file with this extension.
This will associate the txt file with the Notepad and open in it always without any error message. Let us know if it solved your problem.