I find that to avoid this problem you should erase, (or more correctly, rewrite) the MBR before installing. To do this you can use a Windows boot disk. If you don't have windows, fear not! You can download the boot disks from http://www.bootdisk.com/.
Not sure what boot disk will work with your computer, but maybe start with a Win98 disk and use A:\>fdisk /mbr to rewrite the mbr. After doing this, you should be able to reboot with the Linux installation CD and restore the grub bootloader.
Hope this helps,