Cdj 800 mk2 won't load cds for the first 10 minutes?

I just bought a pair of second hand cdm 800s mk2 and they look like their in great condition and the seller was very genuine so i believe they have been kept in good condition etc, 

But every time I've been putting in Cd's they keep getting rejected and sometimes a error message, this happens for about 10 minutes once i turn them on , after that they start to work fine?

Ive tried quite a few different brands of Cds and even friends  Cd's etc?

Thanks in advance