problems with incoming and out going mail outlook 2007

the problem with my outlook is that if i send an email more than 1mb it will continue sending it until i delette it in the out folder and all of a sudden im recieving blank emails with no reciepient or subjuct , who do i resolve these problems ??? ( may it be caused by the bit defender total sercurty which i installed recently)
note :i have deleted all my old mail