It did not start working fine. It still would not actually
upload. The length of the ED2K queue just meant that they got queued properly before trying to upload and failing. It took several hours before uploads progressed to where I started noticing something odd...
Anyway, this time I actually took the time to fix it properly. (Well, I still have no idea why it didn't work but...) I am on win 7 and by default Shareaza uses users/???/appData/local/Shareaza/incomplete. For unknown reason this did not work so I changed the temp folder to something else and partials started uploading. No idea what the problem was. The appData folder has odd permissions, is hidden, and aliased and is in general weird... To be honest I already hated appData because the totally unnecessary trouble I had copying my Firefox and Thunderbird profiles due to it being hidden and this experience did not really help.
Does anyone know if this was particular to my system or is there a general compatibility problem with Win7?