Researchers have discovered one of the first pieces of malware ever used
in the wild that modifies the software on the motherboard of infected
computers to ensure the infection can't be easily eradicated.

Known as Trojan.Mebromi, the rootkit reflashes the BIOS of computers it
attacks to add malicious instructions that are executed early in a
computer's boot-up sequence. The instructions, in turn, alter a
computer's MBR, or master boot record, another system component that
gets executed prior to the loading of the operating system of an
infected machine. By corrupting the processes that run immediately after
a PC starts, the malware stands a better chance of surviving attempts by
antivirus programs to remove it.

http://www.theregister.co.uk/2011/09...it_discovered/

--
Dave - exactly what *I've* suspected for years! ;-)