Unable to block/unblock contacts in MSN Messenger

[Ale]

Whenever I try to either block or unblock a contact by right clicking on it
in the contact list the action won't be performed (the contact still shows in
the same status as before attempting the change). When i right click the
contact in my contact list it says either "unblock" or "block" as if they are
blocked/unblocked but there's no red circle next to their name to say they
are blocked in the first case.When I log out from MSN a sign will pop
displaying the message:"Contact X (the one I tried to block/unblock) cannot
be blocked/unblocked. Please try again later".
Is this a server issue or a problem with my MSN installation? I haven't done
any changes to MSN, it was working fine all these years until this issue
appeared all of a sudden. Any ideas to fix this? Thanks.

 

[Fik]

Same "feature" here.
I have two msn accounts (one for family and friends and the other for work) and every time I log on either it asks me if I want to accept almost all of my contacts.
If I block someone the red circle does not appear but the menu item changes from "Block" to "Unblock", suggesting that the block operation succeeded.
Every time I log out or log in I have to click "Ok" on a message box saying "Unable to block / unblock such and such" for most of my contacts.

A possible unrelated phenomenon (but started at the same time) is that after several hours online, something begins to make every few seconds that "click" sound IE makes when loading a page. The sound stops if I exit messenger (not only log off and close it to tray).

Tests I have done:
1: I have tried t block myself on the other account and indeed it blocks/unblocks me, it only does not add/remove the red circle on the online picture.
2: I have tried on two other computers at home and one at work. Same behavior.
3: I have tried using the Pidgin i.m. client, and surprisingly it shows the same behavior also (different message boxes, of course, but same message).
4: I have changed my password, just in case (no change in behavior)

2 and 3 suggest that the problem is not in my (our) messenger installations nor version. I have considered installing the last messenger Live (that I don't like, I use version 7.0.0820), but I suspect it would not solve the issue.