Very unlikely SP1 is at fault but you may have gotten some new drivers installed at the same time. (Make sure your Windows Update settings do not have "treat recommended updates the same as critical updates" checked if you do not want drivers installed automatically).
If you got a bad driver you can use the Control Panel > Device Manager to "roll back driver" to a previous version. If it did come from Windows Update, then unless you change the setting I mentioned above it will be reinstalled again the next time Updates run so you need to manually check for updates and then right-click and "hide update" of the offending driver.
It's also possible your hub has gone bad. Have you tried plugging your external HD directly into the USB port rather than going through the hub? If that works then your hub could be faulty or there may be hub drivers that need rolled back (I'm not familiar enough with USB devices to know if the hub, itself, would need drivers).
