This happens when PCManFM (file manager & desktop program) doesn't start correctly. You can logout & in again or right-click to find a 'Run' box and start pcmanfm that way. (I've bound Win+R to the Run box but that's another matter) I'm not yet sure of why this happens!
now I have a new problem. I can't login as normal user. there's a message 'cannot execute login' I was follow the other tips on this forum, but it still doesn't work.
and I always think "this is really fun" because I can recognize my own computer and my slitaz.