IP for yahoo messenger possiply hi-jacked

To all my friends that are in contact with me /us through our yahoo messenger plaese accept our appologies if you recieved any rude /crude messages on your IM between the dates of 10 April till the present..............I am investigating it myself and we sent no IM's out to anyone in this time period. My Wife recieved a alarming one today at work while I was at work but it seemed that it came from me when I was clearly off line. Again our appologies and the IMs if you recieved any wernt from us Thank you Kev n Bonnie