Did you delete the whole system mechanic suite or just the anti-virus?
I have seen some issues with System Mechanic and uTorrent.
MC's post goes towards what I was thinking: that something has messed with your system to auto-corrupt uTorrent.
I would like to see if this is a residual issue just with uTorrent.
Try downloading and installing BitComet. During install, undo the browser integration, de-select their home page and comet options and un-check the option to start Bitcomet on Windows startup.
http://www.bitcomet.com/doc/download.htm
After install, go to
Tools>Options>Connection and make sure
Enable NAT/Firewall configuration in ICS/ICF (XP/Vista Only is enabled. Also, set the listen port to the same one as uTorrent's (do not have uTorrent running at the same time).
BitComet should show right away whether DHT is connected on the bottom gray line near the right-center.