I noticed this on version 4 first preview after pressing header update and it got interrupted by the router dropping off line. there seemed to be a negative index created. It seems that there should not ever be negative for index
Bug Data1:
jjj211++1
Bug Data2:
List index out of bounds (60)
I have astraweb setup for my downloads and just use giganews to get headers with the gn accelerator.
this error would keep looping........ over and over I had to press the X to close newsleecher.
I noticed if auto update was disabled the error did not occur on next program startup.
with the program running and in an off line mode I went and clicked update headers. this fixed the index again.
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Well it seemed like it did it ran for a few hours downloading but as soon as I canceled an item from the download list it started repeating again.

Bug Data1:
jjj211++1
Bug Data2:
List index out of bounds (60)
I hope this helps you find this problem