I'm using the dutch-language version of limewire and I got the same problem.

I already discouvered that the message "can't move file to library" (or whatever the exact english translation may be...), this message only appears downloading filenames that are longer than some caracters. I don't know how much exactly, but files with short names, cán be downloaded.

Further I found out that lw does do sómething, when I changed the maximum permitted simultaneous downloads in the preferences-pane into zero. Now lw does do somthing else, but still not really downloading very much. (maybe because it's zero now....)

My os is 10.1.
Lw version 2.8.6