The snapshot shows three threads which seem to be waiting for DropboxExt64.27.0.dll to return icon overlay information.
No other threads are active, except for a fourth thread which is waiting on one the other three to finish.
So this looks like an issue caused by Dropbox.
I would try using ShellExView to disable the Dropbox extension.
- Download the x64 ShellExView, extract it and run it.
- Sort by the Type column and scroll down to the Icon Handler and Icon Overlay Handler ones.
- Right-click the DropBox extension(s) and select the option to disable it/them.
- Reboot.
If it does still happen, please send further process dumps, so we can see if same thing is still happening, and it's not disabled somehow, or if it moves elsewhere.
