My host is 64 bit Windows 7 bit where my VirtualBox is running 32 bit Windows 7. I have installed guest services and I have enabled drag and drop in Settings >> General >> Advance to bidirectional.
I can copy/paste text file between host and virtual box and copy/paste or drag/drop doesn't work.
I have tried one of the solution here by Sam there (Kill VBoxTray.exe) but it didn't work. I see other threads like this but there are no answer.