Problem with 7.5 and Passport

I have recently upgraded to MSN Messenger 7.5. On my PC my wife and I
both have logons. Previously we both used Messenger with no problems,
however since the upgrade she has no trouble but I can't log in and
always get the message that There is a problem with my Microsoft
Passport. However I have no problem on websites with my passport, for
example the MSN site and no problems logging into web messenger or the
older version I still have at work.

Does anyone know if there is some different authentication in 7.5 of
the passport that is for some reason failing?

Many Thanks

Tim.