Background Change Problem

Hi Everybody.
I'm not normally one for posting advice-begging messages, normally prefering to work things out for myself (as I have done with everything since I got my 1.5 PSP a couple of months ago :D ), but this has me totally stumped. I know that the backgrounds are supposed to change monthly, no problem with that, but mine doesn't! It was stuck on green from February into March. About a week ago I flashed the firmware with my own images using PSPersonalise, and it's still stuck on the previous months image. Any ideas anyone? Its a nice image, but I just want a fully working PSP, and this is worrying me a little. Cheers in advance for any help.
Mutantllama

Ignore this post people, background just changed inbetween game loading!!!