Does Thundergird Crash when to many Emalis in Inbox ??

[Jim]

FC8
Does Thunderbird crash when you have  to many emails in Inbox ??
I have a friend that has had thunderbird crash three times in one year 
he says he has 600 emails in Inbox, and I check to see how many emails  
are in his inbox and there isn't 600 email there. But he does leave a 
lot of emails in the Inbox.
You try to read emails and they are not emails from the person that sent 
them ,they are from someoe else.
Is there something wrong with Thunderbird that causes it to crash, when 
you get to many emails in the Inbox ??
Is there a better email browser, not Evolution.
Is there a virus out there that affects email boxes, he gets email from 
all over the US, I have never seen one person get so emails as he does.