[syslinux] boot fails on some system

[Jethro Tull]

I used syslinux to make an external usb hard drive booting up "system rescue cd" from a FAT primary partition.
The procedure I followed was setting on the boot flag on the FAT partition and copying the content of the iso image to it and renaming isolinux to syslinux wherever needed. I then unmounted the device and ran "syslinux -d /syslinux/ -i /dev/sdxn" where sdxn is the appropriate partition. It worked nicely on both laptops i have at hand.

Then I wanted to try the same using an ext2 partition instead and so using extlinux. For this, after creating an ext2 partition, moving the boot flag to it and copying the live linux files, I copied the file mbr.bin from the syslinux package to the hard drive mbr. Then I ran "extlinux -i /mnt/mountpoint". This time booting up "system rescue cd" failed on one of the two laptops. Afterwards even retrying to boot from the FAT partition resulted with the same computer in failing. I hadn't saved the initial mbr content, so couldn't restore it, hence mbr.bin should still be in place and this might be what the failing laptop doesn't like.

For the diagnotics I used the dos BIOS program from UBCD, here is the output for both laptops:
failling /// success laptops :
           Q:\USR\BIOS>bios i
           # Found FreeDOS 7.10 running                      /// same
           # Found unknown BIOS                                 /// Found Phoenix BIOS ???
           # BIOS date: 02/18/06 (month/day/year)         /// 12/26/08
           # State of RTC battery: Full                            /// same
           # ROM BASIC: Not implemented                    /// same

           Q:\USR\BIOS>bios x
           # Found FreeDOS 7.10 running                    /// same
           # Advanced Power Management not activated or not available
                                                                             /// same
           # Found Plug and Play-BIOS v1.0                 /// same
           # Found PCI-BIOS v2.10                              /// same
           # Found IBM/MS Int13 Extensions v0.2          /// Found IBM/MS Int13 Extensions v1.2
           # Found System Management-BIOS v2.31     /// Found System Management-BIOS v2.4
           # Found Desktop Management Interface v0.0 /// Found Desktop Management Interface v2.4
           # Found VESA BIOS Extensions v2.0            /// Found VESA BIOS Extensions v3.0
           |_ # Found VBE Power Management v1.0      /// same
           |_ # Found VBE Accelerator Functions not activated or not available
                                                                             /// same
           # PCMCIA Socket Services not activated or not available
                                                                             /// same