Desktop Icons freeze and desktop becomes unresponsive

About 2 weeks ago I began experiencing this problem. When my computer has been idle for awhile with Google Chrome up, all of a sudden Google Chrome freezes, all of the icons on the desktop freeze and they are all non-responsive. However, when I click on IE or Tune Up Utilities in the task bar, they work. I can continue to use the internet just fine using Internet Explorer. Ctrl-Alt-Del will not work. I recently installed Malware Bytes and a few weeks ago uninstalled McAfee and installed Bit Defender. Other than those two changes, I have made no other changes to my computer.  In addition, on occasion when the freezing occurs, the entire screen will turn white except for that the icons still appear on the desktop but nothing works, everything is frozen. All I can do is push the off button to turn the computer off. When I turn it back on, everything works like normal until much later in the day. The frozen icon issue happens at least once a day. The white screen happens about once a week. What is going on? This is unlike anything I have seen before. I regularly scan for viruses and malware and always have my anti-virus program on. No viruses or malware are there. I turned off Malware Bytes to see if that might be the issue but it still happened.  I have not tried to turn off Bit Defender because I don't want to be vulnerable to any viruses. I use Windows 7. I have run chkdisk and there are no issues that show up