CDJ2000NX Media or File is collapsed or unavailable - E8302

Hi,

I can see that this problem is a relatevilycommon issue. So I have updated Rekordbox and Firmware in the CDJ. When I export tracks from Rekordbox to the USB stick and plug into the CDJ2000NX I get in quite manytracks this message in the screen "Media or File is collapsed or unavailable" and then E-8302

I have checked forums in here and other sites and I didn't find a proper solution. So could please anyone or Pioneer moderator pleasehelp to fix this issue?

It is a very expensive cdj to have this issue.

Thanks in advanced