Using a mouse wheel to scroll through a view quickly while the Notes preview pane is open intermittently results in the following errors:
"'Opening preview' has encountered a problem"
"CLFNM0257E: An error occurred trying to get a previewer from COR. Please contact your administrator"
"CLFNM0257E: An error occurred trying to get a previewer from Widget is disposed"
Restarting the client resolves the issue only temporarily until you scroll quickly through the view again.
Resolving the problem
You can avoid the issue by scrolling slowly through the view.