Thanks Paul F. I have tried it . I am using a windows 10 browser on my Tochisba Laptop. I thought it was the browser so I switched from using Internet explorer to Chrome and the problem is still persist. On trying Notepad++ and others it works but I wish to stick with my intel xdk windows. If it continues then I will just have to quit the app. I am basically stocked. Thanks for an urgent reply.
If all you are doing is developing web app code I recommend that you download and install the standalone Brackets editor (which is the same editor used in the XDK) and use the Chrome simulator to see how your code looks on a mobile sized device (which is very similar to the mobile viewer in the XDK).
If you are taking the EDX course they have already notified their students that they will no longer be recommending use of the XDK for that course. That course, as written, also works well with Brackets, it does not strictly require the use of the XDK to complete the course, many people have completed that course using Brackets.