I've checked your permissions, the resource manager (downloads) settings and any related media upload settings. All is in order. I'm guessing two things:
1) It's a hiccup/anomaly like you suggest - try again.
2) Something is up with the file name...but I can't imagine what that is judging from what you list here in this support ticket.
Maybe try again and see if it occurs again. The one thing I will say is that I too am familiar with uploading/downloading on member based websites. Unfortunately, the forum software is a little goofy for my taste. Make sure you read through Robert's write up I linked to previously so that you get a feel for how the forum software is structured. It is structured this way so donating members have media/download privileges and also keeps a tight rein on what gets in (hopefully nothing illegal - this is a family friendly site afterall)
Anyway, give it another try after reviewing his write-up. Something might jump out at you as obvious.
Bryan