As some of you insist on not using project directories in maya to organise your files you will be finding that stuff becomes disconnected. Unfortunately Maya does not use relative paths (very annoying). You can switch them to relative paths by saving as a .ma and altering the path in a text editor or......
you can use this awesome script on Creative crash that manages it for you
LINK (FileTextureManager)
If someone sees Pete point this out to him as he is having to fight with this at the moment
