[Exitao]

Hi! It sounds to me like it is probably a problem with the file format (i.e. encoding).

What's the file extension? Depending on your ROM, you may have access to more or less media types and bitrates.

Use a conversion utility to convert some of them them to wav and see how that works.

I've seen strange things too when it comes to where a ROM will recognise ringtone and notification sounds. Usually, placing a file on the root of the storage card will make it recognised as a ringtone.
This doesn't always work for notifications (e.g. alarms), whereas it seems to only work on my current ROM if I convert it to a wav file and place it in the Windows directory of the device.

I find this annoying as he... um... heck. I used to have this type of problem on my smartphone (HTC Tornado), but when they finally got stable WM6 ROMs running on it, it suddenly found most mp3 files acceptable for all uses, regardless of where it was stored.
If anyone does know how to make that work, please let me know.