I have a Sansa Mp3 player and I found through trial and error that it won't display the album art on the player if the size of the album art tag is greater then 32 KB, regardless of the dimensions. I also found that the dimensions of 300 x 300 is about right for that size file. That's one of the reasons I started using Mp3tag is because it displays the size of the album art tag.
I use FastStone Image Viewer to resize the image to 300 x 300 and under 32 KB, but there are many other image processing programs that will do the same thing. Most of the album art I've found on the internet is between 300 x 300 and 600 x 600.
The Blackberry might not have those limitations, you'd have to experiment a little to see what they are.
That shouldn't be caused by album art, there's probably something wrong with the tag headers in the Mp3 files.
Get MP3 Diags to analyze and fix the problem files.
I tried many different file size (as low as 10K!) and different image size as well.
My findings tells me that no matter the image size, it's the file size of the image that is the culprit.
No matter how small the file size of the image is, it will stop playing the mp3 file before the end.
Say I embed an image that is 50K, well the mp3 file will stop playing 50K before the end of the song.
Even with files lower than 32K it does the same thing.
Knowing that, do you think it's possible that (like you said) in the header there would be something that tells that the mp3 file is XX in length but is in fact bigger because of the remaining KB used by the embed picture?
How can I fix that?
BTW I also tried many different music software for this particualr "blackberry" and it does the same.
I guess my next step is to update to the latest MP3TAG software and try again all the possibilities!