Firefox Not showing Text

[Joseph]

Just this morning, I got an eMail (in Thunderbird 2.0.0.12) from my 
daughter in which I could not read the text.  It appeared completely blank.

Then I hit "reply" to ask why she'd send me a blank eMail.  When the 
reply came up, there was the text of our previous conversation as well 
as her last comments.

I didn't add any programs yesterday or this morning, so what could have 
happened and what can I do to get text in the preview pane of my 
Thunderbird without hitting "reply"?

Joseph