Dear Rafael…
I’ve tried rename my project folder (copy to another ExHDD) and reconnected all the media offline..and it’s now working perfectly fine!! Thank you soooooo much for your attempt to answer my question…it save my life ^___^
Anyway, I’m still wonder if my last external hard disk could coz the problem…as every time I connect it to my (very new) iMac..my computer become slow down and unresponsive…and take sooo long to open and transfer the files..)??!