My last windows update date is Oct. 17 according to the windows update history, but I updated the graphics driver to ver. 24.20.100.6290 on 25th on my pc supplier's site. The strange thing is that I was able to use SL as usual until around 5pm 26th.
I tried updating the graphics driver to ver. 25.20.100.6326 on Intel site to no avail.
I'm going to ask the pc supplier what the version of the driver was so I can roll back the graphics driver to see if that helps.