"?" symbol appears instead of letters

Hello,

My colleague has Win7 Ent. and sometimes, some senders in Outlook 2007 appear in "?" symbols. In attachment also IE10 pop up from Linkedin, this time another symbol, so its not only Outlook affected. Emails are from Russia like the other ones that works fine.
Any one experienced something like this?

thank you
Cali

Sounds to me like the first thing to do is determine what Font is being used in the sent messages and assure it is installed on the recipient's computer.