MSN login trouble & itunes error

Posting for a friend...

MSN allows young brother to login but not older brother - error code given relates to a time/date problem but clock is synched ok.

itunes allows music selection for downloading but gives a gateway error just before downloading starts.

Yeah, I know this isn't a lot to go on but I was just wondering if anyone had come across these problems before?

 

A bit more information - if the computer is restarted, the first person to login (XP) will get msn to connect but the pc needs restarted for someone else to login to their msn (this is why older brother also couldn't download from itunes - he wasn't the first person to login to xp after a restart and was denied access - if he logins in first after restart then he has no trouble...)