Older Logic songs won't open..

Hi

Recently, when trying to open song files that opened fine a few months ago, I get the usual Logic startup stuff - checking midi instruments etc. - and then I get the multicoloured spinning wheel, which stays there until I have to force quit. So basically the songs don't open..

I tried removing plugins from the audio library on my hard drive but to no avail. My plugins are legal copies too.

Any suggestions?

Thanks