Vanishing Email - XP/Outlook

Greetings Troops,
I have an odd occurance with XP/Outlook. Email comes into the program OK. I click on the email and view it in the preview box OK, when I click on any other folder (example: sent)the email vanishes totally. I did a search for the title on my hard drive but it is not there. I sent several emails to try to find where they are going. Nothing doing! My question is this, do I have some odd virus or is there some settings that my be hosed up causing my emails to be blown away automatically? I'd appreciate any of the guru's thoughts and help.

SES