#1 cure to try first is turn the computer off. Wait a couple of minutes, then restart. 

#2 Try the new Lacerte Tool Hub https://proconnect.intuit.com/community/help-articles/help/fix-common-problems-and-errors-with-the-l...

#3 The only other suggestion is to call support and they may be able to help you cure this. https://proconnect.intuit.com/community/taxation/help/how-to-contact-lacerte-for-help/00/4691

P.S. I did find this article for ProSeries, but I don't see much that would apply to Lacerte. https://proconnect.intuit.com/community/manage-passwords/help/sharing-violation-the-process-cannot-a...