The log is EXTREMELY short. Is it supposed to be? Here are the entire contents of the mbr.log you wanted:
Stealth MBR rootkit detector 0.2.4 by Gmer,
http://www.gmer.net
device: opened successfully
user: error reading MBR
kernel: error reading MBR
I then realised that I did not run it as Administrator (doh), so here's the new log:
Stealth MBR rootkit detector 0.2.4 by Gmer,
http://www.gmer.net
device: opened successfully
user: MBR read successfully
kernel: MBR read successfully
user & kernel MBR OK