I had this problem installing FC3 today - when creating the 4 CDs, the last one didn't get written properly. I know I should have opted to check the media first, but I didn't, and as a result, I went through an entire installation process (all went well) except it needed to get to the last CD for just ONE rpm (reiserfs-utils). Here it went into an endless loop. The media was bad and the file could not be read, and I was not given the option to skip the package. I was hoping I could reboot then (since everything else would have been complete) and install the reiserfs-utils package later. Nope! Grub hadn't been set up! What I think anaconda should do: 1. Install Grub as soon as possible (i.e., right after glibc, kernel, grub itself, whatever else it needs to boot) before proceeding to install the rest of the packages. 2. If a package cannot be read, give user the option to skip it and install it later. I feel this would improve userfriendlyness a great deal - so far the installer's fantastic - this would make it better!
Skipping packages can lead to different problems with booting (eg, in your case, not having the reiserfs tools properly installed would lead to having to drop to single user mode and manually bypass some checks. And installing grub earlier is far less trivial than it seems just due to dependencies on a non-trivial amount of stuff.