Messenger crashing, all contacts offline, can't message any of them

Problem description: Whenever I try accessing my Inbox, or messaging a new contact with whom I have not chatted before, Messenger flat-out shuts itself off without any sort of error message.
In addition, any message I send to an offline contact I have chatted with before does not get sent at all and gives the response ‘‘The following message could not be delivered to all recipients’’

Error code/error message: None, it just shuts down and the little taskbar icon disappears when I mouse over it.

What has been tried so far: I’ve reinstalled Messenger 8.5 countless times and even tried different versions, but the problem persist in one or other shape. It just sends me to a blank or invalid IE page on the older versions.

Messenger version: 7.0 - 8.5

Windows version: Windows 10

offline messages aren’t supported yet; however, they will be when 2009 comes out.

can’t explain the other problem, though.