I've not got one, but I was thinking of it...
You could try updating the firmware. I think most worryingly it's supposed to fix the following problem
"This firmware upgrade addresses an issue which may occur under exceptional
circumstances on the AVIC-F900BT & AVIC-F700BT only. The issue involves
music being played back from the SD or USB sources switching suddenly to maximum
volume."
http://www.pioneer.co.uk/uk/content/support/support/upgrade/AVIC_F900BT_F700BT.html
Be interested to know how you get on... the comments I've heard are along the lines of "Niceish product, but buggy and released too early"