Just an update to this…
I have so far deleted the package and recreated it. I have used upload, URL and file browser to the file. I have renamed the file. I have deactivated all my plugins, I have updated all plugins, themes etc. I have deatcivated the Download Manager plugin. I have regenerated the download key. I have cleared the cache – still it is not working.
The LinkedIn button remains blank when you hover over it and the Twitter Follow just downloads a text file which I have attached.
This is happening on ALL of our downloads.
This is now causing us very serioud problems and needs resolving ASAP.