I have received a reply from support which talks about mp3 files which doesn't really cover my problem (copy below) but it suggests upgrading the firmware, which I assume will be free at a Nokia SC. I will try this first and see if this makes a difference and if not send it back as offered. Current version is v3.04.35 12-05-05 RM-36 if anyone else has had similar problems with this release?
Thank you for contacting us with your issues regarding the memory card and jittery video quality.I would suggest you to kindly look at the following steps to check for the problems you are facing with the memory card :
1.Patch mobile to latest firmware (If Nokia mobile, at local Nokia Service Centre)
2.Experiment with different utilities for converting your CDs to MP3.If a Nokia mobile try .AAC files (which is the native playing format in their players).Basic point is not all MP3 files are the same.Different compression codecs do it slightly differently.
3.Bit rate of the MP3 you are playing can be relevant.The higher the bit rate,the harder you are working your mobile phone software.Anything above 128kbps for MP3 on a mobile is a waste of space.For .AAC (even more efficient) anything above 96kbps is a waste,and personally,I find 64 kbps qualities excellent.
4.Faulty phone-Some do have electrical problems that can cause intermittent/erratic performance on music playing.
5.Faulty Memory card-It is always possible that the memory card has a physical fault.
Very occasionally this will happen.Of course,we are happy to replace on warranty no problem if it was this issue.
Other things can also have an impact,such as local signal strength (can affect the available resources on your mobile).Have you got a friend with another card you can try as well. Might help you work out your problem...
Also try out your mmc on 2 a different phone to check if the hardware of your phone is rite or not.
Sir,if you still think that the product is corrupted then you could definetly go for a Replacement