Thanks for your reply.
1. That's what I thought, but the weirdest thing is I just noticed that it seems to be working after I shut down Windows, it seems the change did not take effect immediately.
2. If it start to happen again, I'll clean up my style list as recommended (there are a bunch of styles created after pasting).
ps: do you know of any other free editor that won't transfer styles, it seems Notepad just remove hiperlink and text formatting (bold, italic, etc.) but not styles (paragraph spacings, etc.)?

Thanks again for your reply and recommendation.