As an IT guy who runs a managed anti-spam service for quite a few clients, my advice would be to:
- ignore the bouncebacks to your legitimate address from people and automated responses complaining about things you're apparently sending to them (but in fact most probably aren't)
- confirm you're not in fact the sender of the spam by doing a full scan of your PC with an updated antivirus/antimalware package to ensure it's not you that's been compromised
- read bounces from automated systems carefully when you have received one from an email you yourself tried to send. Most of them will give you instructions (possibly slight hidden amongst the bounce info) about which RBL (Real-time Blackhole List) your address belongs to. Your task then is to visit the relevant website for that RBL and register to remove your address from that RBL.
Cheers,
Mike (posting from sunny Belarus this week)