Mad Crow!

Does anyone have any ideas or suggestions about how we can deter a very persistent crow from trying to break into our house? This started about a month ago when we noticed strange marks on our glass doors and windows. Then, one morning at about 5 am we heard this racket from downstairs and crept down to find a huge hooded crow flinging himself against the glass doors. Once he had exhausted himself doing that. he stood tapping furiously with his beak (good job we've got toughened glass!) This now happens on a daily basis . We have just returned from a wedding in France and, not only has he tried to attack the doors through the grills that we put up when we go away, but he has trampled down my geraniums in the window boxes to get at the windows.He is getting more and more bold, as yesterday evening he stood tapping at the kitchen door while I was cooking. (good job the door was closed!)Does anyone have any idea about a reason for this strange behaviour or how we can stop it. We are fed up cleaning the doors and windows, and before anyone suggests it, we do not own a shotgun:-)