System: Mac OS X ver 10.4.11
It all started when a client gave me a pdf file to change some wordings created by their in-house artist. The problem is, I can’t open it unless I know the password. I asked the client but the artist is not available, grrrr :(. Oh well, search…, search my hard drive, browse the web…time is running out..

eureka! It’s Mac OS X’ ColorSync.

Open the file and save as. That’s it! Now I can edit this pdf file.