ok, non l'ho postato perchè subito dopo aver fatto questa procedura il messenger cmq non funzionava. dopo 2 riavvii ha misteriosamente ripreso a funzionare
Click START>RUN and type the following

regsvr32 softpub.dll Wintrust.dll Initpki.dll Rsaenh.dll Mssip32.dll Cryptdlg.dll

then press ENTER.

If you use Windows XP you should open another run window after running the previous commands then type the following command:

regsvr32 Dssenh.dll Gpkcsp.dll Slbcsp.dll Sccbase.dll

and press ENTER again.That should solve the problem took me 2 days of searching google to find that but I had the same problem. By thew way this is a very interesting web site where I found the help

http://www.msn-problems.com/solve-m...senger-problem/

hope this sorted your problem.