Some downloads suddenly restart downloading from 0%

Okay, here's the deal: I have an G4 PowerPc iMac (1Ghz) and a good ADSL connection (I think). I use the 3.6.15 version of Limewire and have this problem with some downloads: the file is downloading fine but suddenly it dissapears from the top of the list and I find it on the bottom of it saying 0% downloaded and the download starts all over again. This is really annoying 'cause I downloaded a whole Monty Pythons film once (600 something Mb) and it reached 99% and restarted. After about 3 or so times I went to the incomplete folder and, after canceling the download, clicked on the file and found that it was actually complete so I took it and renamed it and have it sitting on my shareds.
I later found that when this happens, if I cancel the download and then go to the incomplete window on the Limewire library window, I can actually find the file on its pre-restart state and resume the download from there, so that if the download restarted at, say, 75% I can resume it from 75% and not from scratch.
All I wanna ask (finally) is " What the heck is causing this problem and, if you know what it is, can it be fixed?"
Sorry for that useless rambling.
Thanx.

Oh, btw I use OSX v10.2.8