Moderator Notice
Firstly, why force responders to download a thumping great RTF and load it into a suitable application just to see a Windows error message image. Why not paste an Alt+PrtScrn snapshot into Paint, save it as a jpg or png and attach that. I've done it for you.
Did you check that none of the calibre components were running by thoroughly examining the Task Manager list, maybe something was running, a server or a command line program, or the viewer or the book editor.
BR