Repairing doesn't work at all.
I even went to %APPDATA%\Roaming\Microsoft\Office...
and deleted all the files there, including those under template
It didn't work, either.

I turned to the last resort then - reinstall Win7.
It worked, but it was hassle. Doesn't seem, uh... not sensible. Turning the OS over for a program in the OS...

I still don't know where it got wrong,
maybe registry... just a guess...
As a novice user of the Windows OS, the best I could say, every time when there's a problem (strange problem) and I couldn't google a solution, I would say there's something to do with the Registry.

But thanks for your follow-up.