Weird problem with Sansa e270

My Sansa e270 was working fine and then one day it simply started refusing to recognise new songs that I add. Up until the problem occured I had been using it in MSC mode, like a hardisk, adding songs by dragging and dropping them into the music file. Now it always defaults to MTP mode and changing the mode in "Settings" makes no difference. Another symptom is that when I turn it on it takes ages to start up and always goes to the language screen. When I connect to the PC in either mode it seems to work fine, like it always did, but when I disconnect it does not do the "reboot" thing anymore, and doesn't recognise the changes to the content that I have made. If I remove a song or an album, for example, the player's menu still thinks it is there, but of course it won't play the song (if its been removed). New additions are simply not recognised by the menu. I thought about formatting the entire unit, but, if I do and I can't add new songs (i.e. the problem doesn't fix itself) I will be left with no music, whereas, now at least I have the same songs I have had for the last year. What do you think I should do? And thanks to anyone who has read this far and is thinking of suggesting a solution. :)