Error: Unable to move RecycleBin.ffs_tmp\<...> to the recycle bin.

[roytam1]

I'm getting following error in ffs log:

[9:16:53] Error: Unable to move "Q:\slave\fileroot\RecycleBin.ffs_tmp\somedir\someotherdir\Chapter 1\Chapter_1\Ch1_expt_e.ppt" to the recycle bin.
[9:16:59] Error: Synchronization completed with errors

what's wrong with it?