The common opionion on these forums about Incredimail is to NOT use that program, I'm afraid.
Remove it (from Config Panel Add/Remove), reinstall it and if the trouble continues go and search for another email-client.
I am using IncredimailXE and no matter how I try I can't get the answer from them. Does anyone know why my emails would be coming in duplicates and not all will load..I get 'Operation Incomplete' half way through. I did a virus scan the other day and found 3 infected files and over 100 encrypted files with 'Spybot' which I recently uninstalled.