I just got a new computer running win8.1, and installed my x7. Surprise!!! No thumbnails. I'm working blind here. I have all the updates installed. Can anyone help me out? I'm not a programmer.
Short and simplest answer to your question, is to remove and re-install the Corel Graphics Windows Shell Extension.
To do so, from the Control Panel, go to Programs and Features and once it lists the installed programs, click on the Corel Graphics Windows Shell Extension and remove it.
Then open up Windows Explorer and navigate to C:\Program Files\Corel\CorelDRAW Graphocs Suite 17\Setup\CGS17. There, run ShellExt.msi. This will install a fresh copy of the Windows Shell Extension, enabling you to see the thumbnails.