Track stutter and wrong BPM display Rekordbox / CDJ-850

I have had problems with sound and information on my CDJ-850.

1. The tracks I have on my USB-stick, transfered from Rekordbox does not show the correct BPM information that Rekordbox has added.
   For an example. I have a track X on my Redkordbox, it says its 140 BPM after it has analysed the track. When I transfer the song to my USB-stick and puts it on my CD-player. The BPM meter shows that it is 150 bpm (Which is false).
   I have re-uploaded the song to my USB stick a few times just to see if I can correct the problem, but the CDJ-850 keeps showing 150 BPM.
   This comes to many other songs I have, Some tracks that are 185-195 are often shown in CDJ-850 that they are only standard '180 BPM'.

Is there anyway I can manipulate the BPM calculator on my CDJ-850 to re enter new data or can I do something in Rekordbox that will solve my problems?

1. Some of the tracks I have transfered from Rekordbox to my USB-stick is stuttering, It keeps its tempo but you can hear stutter in the sound a bit here and there, and when its a lot of sound, it starts to spark and sound like a bad speaker.

The files I use is 192kbps MP3 files, The stutter does not come up on my Rekordbox when I play then on my computer.

I won't rule out that it is perhaps something wrong with my USB-sticks, but I wanted to mention it, if someone else does have the same problem

I have, and have only had v.2.02 of Rekordbox

My CDJ-850 is about a week old now.

Thanks in advance

//Fredrik