It appears that the RBFG boot floppy (again, sigh) randomly overwrites the word at address 0x5700 with the value 0x0025. As luck would have it, in pxelinux 2.08-pre6 this changed from "harmless" to "catastrophic" because of a shift in variable addresses. I have released 2.08-pre8 which avoids using this memory location completely. It also changes the filename limit in pxelinux to 127 and the max number of labels to 64. ftp://ftp.kernel.org/pub/linux/utils/boot/syslinux/Testing/ -hpa