Clever, isn’t it. I was trying to install Microsoft Security Essentials on a laptop running Windows XP Professional; installation kept failing with error 0x80070643. Picked up hints around the web that other anti-malware programs might be interfering. I had already uninstalled Avira AntiVir Premium, but though I might as well try getting rid of Microsoft AntiSpyware.

Surely these two Microsoft security products couldn’t be conflicting with other…surely not…oh. Yes they could, it seems. Removed Microsoft AntiSpyware and Microsoft Security Essentials installed with no problems. Something for Microsoft to sort out, I think…