This is a SOFTWARE problem, i've seen this before many times, quite popular with Nokias too if they are high spec.
Try resetting your Sony ericsson in settings to see if it clears it but back up your photos onto a memory card first & contacts etc.. If that doesn't work you will need to have the software upgraded.
This also can happen if your inbox/sent box etc are extremely full so if you haven't deleted them from the phone itself get rid of the lot.
A phone as new as that may still be under warranty too so check that 1st before you part with money at a phone shop/repair centre.
GATORS
Craig
October 2008