I assume by parts you means download threads?

I recently had a spate of java crashes which was put down to nod32 and a fix for that seemed to generally work ending numerous crashes.

But I did notice on fileserve you do occasionally get "difficult" files (even if others in a set download normally) to download which tend to stop pause restart etc (I suppose the server is in Timbuktu). Trying to download one of those files did sometimes cause a java crash for me. The solution for me and those odd files was to only have one download thread and although those files still stopped and started as usual, they do download now without any further problems.