The first stage boot loader has been loaded and started, but it can't load the second stage boot loader. The two-digit error codes indicate the type of problem. This condition usually indicates a media failure or a geometry mismatch. The most frequent causes for a geometry mismatch are not physical defects or invalid partition tables but errors during the installation of LILO. Often these are caused by ignoring the 1024 cylinder boundary.
This error code signals a transient problem - in that case LILO will try to resume or halt the system. However, sometimes the error code is not transient and LILO will repeat it, over and over again. This means that you end up with a scrolling screen that contains just the error codes. For example: the error code “01” signifies an “illegal command”. This signifies that the disk type is not supported by your BIOS or that the geometry can not correctly be determined. Other error codes are described in full in the LILO's user documentation.