warning -- PREP I -- preferred load address not found in mapfile filename; assumed address
Current versions of the linker list the preferred load address (that is, when the EXE gets loaded at this address none of the run-time relocation addresses need to be fixed up). PREP needs this information. Somehow this information was missing from the mapfile. If the latest linker was used, the mapfile was probably edited. Regenerate the mapfile, retaining the line that states the preferred load address.