Direct Folders Error: "An outgoing call cannot be made since the application is dispatching an input-synchronous call."

When I try to open/save a file picking path from an open window in FileBrowser, an error message tells me: "An outgoing call cannot be made since the application is dispatching an input-synchronous call."  (I've translated message from Italian language, in wich the message is explained). Any solution? Any other case? I found this lgooglin in internet: https://learn.microsoft.com/en-us/answers/questions/255683/system-runtime-interopservices-comexception-an-out