Mass file download starts after "download all headers"

[calberga]

Running under Windows 10.

I was off line for a while. Today I did a "download all headers" and the Newsbin program immediately started files. By the time I opened the download list, found the "select all" and deleted all it had downloaded over 1000 files.

What have I done to deserve this?

I.e., how do I prevent this from happening again?

Please tell me what other information I need to provide to find the glitch.

An addendum: It has just occurred to me that the downloads probably started when I opened the list of item for one of the newly refreshed groups, not when the header download finished.