Adobe Download Manager.
The first thing Adobe Download Manager does when I try to download Reader 6.0.1, is deleting my existing 6.0.0.
Using the same file name for both versions is also stupid - if I am prompted if I want to overwrite the old file, I assume I already have the newest version, and answer
no. The version no shown in the properties pop-up, is not 126.96.36.199 - it is 188.8.131.52 !
Microsoft is not a monopoly, at least not when it comes to stupidity.
(I am stupid too, I should have checked "Do not use Adobe Download Manager")
I did, but nevertheless it turned up somehow....