Message d'erreur Windows 7

Bonjour,

Depuis quelques jours, lorsque j'éteind mon ordinateur (iMac 2008 - Windows 7) un message d'erreur dans une cadre bleu s'affiche.


Ce message dit :
A problem has been detected and windows has been shut down to prevent damage to your computer.
A process or thread crucial to system operation has unexpectedly exited or been terminated.
If this is the firts time you've seen this stop error screen, restart your computer. If this screen appears again, follow these steps :
Check to make sure any new hardware or software manufacturer for any windows updates you might need.
If problem continue, disable or remove any newly installed hardware or software. Disable BIOS memory options such as caching or shadowing.
If you need to use Safe Mode to remove or disable compunents, restart your computer, press F8 to select Advanced Startup Options, and then select Safe Mode.
Technical information :
*** STOP: 0x000000F4 ect.
Collecting data for crash dump ...
Initializing disk for crash dump ...
Beginning dump of physical memory.
Dumping physical memory to disk : 65

Je ne sais pas que faire : Est-ce que grave ? Puis-je faire quelque chose pour résoudre ce problème ?

Je vous remercie d'avance et j'espère que vous m'apporterez des solutions.

Cordialement,
Narkeux