Right, I have stumled across a few sites that have seemed to offer some things, and I will enclose here what I have found.1.
in response to: laidungvn
re: 802SE- Can not play MP3???Help!!! Missing DRM ....
enter code text herehttp://developer.sonyericsson.com/community/message/62088
Now, I myself have two suggestions here for you; the first is that you get the phone unlocked; either by doing this yourself or pay someone a few quid to do so. The second answer is to check out the manufacturers' website and see what support there is for your phone. Now with regards to DRM (Digital Rights management) you might be able to work around this by getting hold of a software converter, and converting your media first on computer before appending it to your phone; its probably worth a shot, so give it a go. In google, just hit up, mp3, mp4, converter or media converter. I know AVS do a converter, but not sure if this is free or not. All DRM is designed to do, is force you to aquire some license or pay for your content, to either use for a pewriod of time, or at limited use. Finding a converter, or actually unlocking your phone might be the only way to get round this; but there could well be legal issues with regard to this, so Before going this way, I would suggest going to the software vendor of your media; and also to Sony Ericsson, in order to find out exactly what the DRM covers; sling them an email in the first instance and see what happens.
I hope this turns out to be the right fixya for you, and good luck