Our company IT have just put this out to staff:
The Multimap web site appears to have become the victim of hacking. If you visit the site you will automatically be redirected to a "Malware Alarm" site warning you that your machine is infected with Malware and that you should download a scanner from their site.
This is a scam intended to download spyware on to your machine. Please do not download any files of this nature.
If you need to use a mapping tool, then better to avoid Multimap for the time being and use something like Google Maps.