I downloaded this img:
$ wget -c http://live.debian.net/cdimage/daily-builds/squeeze/20101229-1/i386/usb-hdd/debian-live-squeeze-i386-standard.img
I installed the first configuring my ethernet. All right. Have you installed the grub-legacy without problems.
Second try without setting ethernet.The ruling is you can not find packages for grub (grub-common, grub-legacy, grub-pc, os-prober).
Activity on target with chroot and see all the sources.list commented.
I leave of target and go to F5, configure the network and replicates of the repositories. I fault the network, back to target and edit the resol.conf, I go. And I come back to set up replicas.
Then go down the packages related to grug-legacy and all right.