I had a client who received this error with the exact same scenario and Sage couldn't duplicate it with a copy of their MAS90 directory at all, so after creating a new user account for the users who worked in Cash Receipts, the error went away. Some of these users were also getting upgraded/new Windows 10 machines at the same time as well, so I can't say for certainty that it was the new user account, but it's easy enough to try.