podivej se do logu : http://windows.microsoft.com/en-us/windows/what-information-event-logs-event-viewer#1TC=windows-7
(Open Event Viewer by clicking the Start button Picture of the Start button, clicking Control Panel, clicking System and Security, clicking Administrative Tools, and then double-clicking Event Viewer. Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.)
Po otevreni si rozbalis v "Event Viewer (Local)" v Summary of Administrative Events -> Error -> pravym -> View All instances ... a seradis si to podle casu, pokud tam budes mit zaznam o chybe, vyber ten, kterej by mel odpovidat dobe vypnuti pc v dolni casti bys mel mit celkem presne popsany kde nastala chyba (pripadne je mozny exportovat do XML, tak to sem kdyztak hod)