Better test with the 5.1.0b25 version to see if it wasn't an old bug we squashed years ago.
A handy side benefit is vastly improved performance and the ability to force it to ultrapeer mode.
(Not to mention that the betas all came out free of adware.)

Also, you haven't mentioned what version of Windows you are using, but if it is XP Service Pack 2
you should go here and download EventID 4226 Patcher. 4.3.5 wasn't built for SP2 because
it came out long after we released that version. ;]