One rumour that i had heard was that they had very cleverly used the mobile phone network of the area to create a grid pattern dome over the entire area, Serbia, Croatia (sp?) They then knew nearly every movement in and out of this 'dome'
With many movements they were unable to fire for whatever reason. Maybe a lone aircraft was just too much of a temptation!!
Probably just as much tosh as the windows thing....you decide!
Geez