Dlls required for MSN becoming unregistered?

..and saying 'unknown username or password' but if I use this solution as found elsewhere on this side..

regsvr32 softpub.dll wintrust.dll initpki.dll dssenh.dll rsaenh.dll gpkcsp.dll sccbase.dll slbcsp.dll cryptdlg.dll

It works fine again. Any ideas why they are becoming unregistered in the first place?

There is rogue adware/spyware out there, that installs itself on your PC as \program files\MSN Messenger instead of the real \program files\messenger
You may have been 'visited' by it.