I am Sampad from Dell Social Media and Communities team.
This issue might occur if the “Auto Arrange Icons” option has been checked. Step 1:
Let’s try to uncheck this option first and then arrange the icons by grid and check if the issue persists.
Follow this step to do the same.
1. Right click on an empty space on the Desktop-> Click on View.
2. Uncheck the option “Auto Arrange Icons”.
3. Check the option for “Align the icons to grid”.
Check if the issue persists now. Step 2:
Also I would suggest you to reduce the resolution of the monitor so that it will not extend beyond the display area.
Change your screen resolutionhttp://windows.microsoft.com/en-US/windows7/Change-your-screen-resolution
Additional reference on:
Work and play better with multiple monitorshttp://windows.microsoft.com/en-us/windows7/work-and-play-better-with-multiple-monitors
Dell Social Media and Communities Professional