I had just added a new feed, then clicked on the blue down arrow to download all podcasts from that url. Big mistake!
Juice started updating ALL feeds (I have dozens), and started to download hundreds of podcasts. There was no stopping it... hitting the exit button just gave me a "program not responding message", and I was afraid to force it to quit because I didn't know what state it would restart in, etc.
I'm guessing (because I do NOT want to try to repeat this process) that this is default behavior that happens if you don't explicitly select a feed url in the subscriptions list before clicking the download button. (The feed I wanted to download from was "kind of" selected already, because it was gray... but I don't know why, and can't reproduce this.)
A nasty side effect of this problem is that it wiped out my entire list of over a hundred previously downloaded podcasts that I haven't listened to yet. Ie, my previous list of downloads was completely replaced with the new list (queue) of hundreds of downloads that was about to take place.
This happened to me a couple months ago too, but with less "damage" because I only had to abort several dozen downloads instead of hundreds. Altho I had no idea what caused Juice to spontaneously start downloading so many podcasts, I learned enough from it, so this time, right after Juice started spontaneously downloading again, I limited the damage, as follows.
First, I quickly set download threads to "1" to give me time to delete the long list of downloads in the Downloads tab. However, even after deleting the entire list of downloads, each time Juice finished one download a new download would appear on the list, and commence to download.
So secondly, while the next podcast was still downloading, I set the "Stop downloading if disk space is less than..." to several gigabytes. The current download completed. Then fortunately no more downloads started; I just watched the log fill up with hundreds of "not enough disk space" messages as Juice continued to try to download each new podcast in the new list it had created.
(Tell me, did I miss a simple "stop" button somewhere? <g>)