I use Sketchup 8 under Windows7 and if I have Sketchup opened and I drag and drop any file from one location to another, Sketchup crashes !!!
If it's minimised I did not encountered that, unless I drag files on a folder's (or application) icon on the taskbar. It's like SU tries to catch the file, even if the focus is in other window. Somehow it tries to get priority when mouse passes over its window, or taskbar button.
I first noticed this when I tried to send images trough yahoo messenger and I had SU opened. I also lost two Twilight renders from this reason .
This should be a QUICK FIX, if Google guys are reading this, because it interacts badly with Windows.