Windows turns off display, doesn't sleep

I am running windows 7 x64
I have Comodo Internet security (antivirus and firewall)
Radeon 4850x2
And it recently started doing this.
I have the PC networked to a home server running windows server 2003, and recently changed my login on this pc to match the user I created on the windows 2003 server with which it logs in as. (This negated me having to log in twice- once into this PC and the second to a network share on the server.) I'm not sure if this is significant, but it seems like a networked pc would be less likely to sleep.
Things I've tried
- I set both display to turn off and pc to sleep after one minute then:
Unplugged all USB devices
Turned off all Network adapters
Picked up a book

One minute later the PC's display shut off, but still no sleep. Whats the deal?

Windows Media Player sharing?

no, tried it. In fact I was able to get it to sleep earlier. But now it's not, and after some research I've found other people having trouble and referring to windows 7 sleep tendencies as erratic

try turning the power option to anything but high perfomance.

It's on balanced