I'm using Windows 7 on a PC. I can't get acsm files to transfer to ADE 4.5 - each time I try, I get 'ERROR! Check Activation'.

I've read the advice about deauthorising my computer, but when I try it doesn't accept my password!  I've checked, and my password lets me into my Adobe ID account, so I don't know what else to try.  Any ideas?