When targetting a Virtex part the following error in MAP occurs :
FATAL_ERROR:basut:basutpak.c:560:1.3 - Bogus offset reading packed data. Process will terminate. Please call Xilinx support.
This error indicates that a data file is bad. For the case encoutered, the system was experiencing hard disk problems. The problem can be resolved by correcting the hard disk issues and re-installing the 1.5i software.