I am running Windows on my PC. I recently d/l'd and ran memtest86+ on my system, and ended up with a machine that was essentially un-bootable afterwards. The program runs in Syslinux, and so when you reboot to test your ram, it just goes ahead and installs Grub bootloader to your system so it can boot Linux and run itself. Something went wrong and after this I was unable to boot Windows anymore, I could only boot to the memtest utility. Fortunately I have a copy of the Ultimate Boot CD, and installing a boot manager from the UBCD made my PC bootable again.
Am I the only one who thinks that it is sheer insanity to write utilities for Windows that write to the bootsector like this? My own experience is that Grub has done more damage to my system than any malware has ever done.