FYI I'm having the same bug with my Acer Aspire One D150. If I plug in the external monitor, hit "detect monitors", both screens goes black, and the netbook freezes. If I turn on the netbook with the external monitor plugged in, both monitors works mirrored, and at 800x600. If I try to change any monitor preference (like position or size), the netbook freezes.
I then tried disabling desktop effects (i.e. no compiz), and everything worked perfectly, at the maximun resolution (netbook at 1024x600, external LCD at 1680x1050)
FYI I'm having the same bug with my Acer Aspire One D150. If I plug in the external monitor, hit "detect monitors", both screens goes black, and the netbook freezes. If I turn on the netbook with the external monitor plugged in, both monitors works mirrored, and at 800x600. If I try to change any monitor preference (like position or size), the netbook freezes.
I then tried disabling desktop effects (i.e. no compiz), and everything worked perfectly, at the maximun resolution (netbook at 1024x600, external LCD at 1680x1050)
HTH.