A friend of mine in the U.K. (has virus Protection on his PC) has sent me mail via O/Express and when I use the reply button to make a reply to his mail the mail is returned by the Mail Administrator as not delivered etc.

The reason for not delivery is that my friends email address is somehow being corrupted a letter is omitted from his mail address the letter "i" is not being input to the send address.

I have removed his mail address from my address book, but when asking for the re-entry the address is corrupted again.( less the i).

If I go back to August and ask the sender address to be put in (the address book) the correct mail destination is entered.

No other entries in my address book are corrupted, so can I assume that this gentleman has the virus, or is it me.
I use an upto date virus scanner with daily updates.

Help or advice much appreciated.