Skydrive – showing different files on different devices

I installed Skydrive and bought enough storage to deal with all my data.  I then synched my iphone, ipad, laptop, desktop at work and desktop at home and for a few days everything was absolutely seamless.  Yesterday a problem emerged.  On the pc at home (running windows 7) everything is still visible.  On all the other devices the majority of the files are missing.  Some whole folders have gone and some of the sub-folders have gone from those folders which have survived.  I've tried uninstalling and reinstalling on a couple of devices but to no avail.  What can I do ?