If a time is also shown, that means the file is downloading slowly (at less than 1KB/s). LimeWire shows very slow (or quick) average speeds as 0 KB/s . Look in the tools-statistics-bandwidth-downloads and watch the HTTP KB/s--those will show the fractions.

Easier, though, is just to repeat the search. If new sources of exactly the same file are found, LW will add better sources to try.