Hello,
Sorry to hear you are having issues.
OK we're going to try a few things so follow the directions .
First the DS11 key won't work for v8 only DS11.
Next do the Purge again and REBOOT then install DS11 again REBOOT,
now test if still and issue with DS11 the go to your DS11 settings and try
all 3 options ( see image below ) .

**** if still an issue might require your video card might need updating ,
another option is to update your codecs. I use this the KLite Mega Pack ( default install ) Reboot
Link https://codecguide.com/download_k-lite_codec_pack_mega.htm
If still an issue then do a Clean Boot https://forums.stardock.com/485954/deskscapes-support-faq#cleanboot
this will show you if you have a Third Party app causing your issue .
If you try all those steps in that order your problem should be fixed ,
Report back your results .
REMEMBER to do ALL the REBOOTS.
AzDude
Stardock Community Assistant