lost emails

I have Outlook 2003. For the past few days, after loading a new antivirus system (which I have since removed due to the problems with Outlook) my emails download and immediately disappear. I have checked all files, and run the ‘test settings’ option under email settings which records no problems with sending and receiving. I am able to send emails but receive very few. I have spoken to clients who confirm they have sent emails in the past week but I haven’t received them. Where do I find these emails?