Hello again, I have not solved my boot problem and I am going to trouble you all again with it because I would like to get to the bottom of it. I wouldn't call myself a SCSI expert, but I have been building and repairing all-SCSI systems for over 10 years now and this problem is troubling. To recapitulate, in the meantime I have had three SCSI hard disks become unbootable, i.e. the bios recognizes them as boot disks or partitions but they will not boot in spite of the boot files being present. The SCSI parameters in the bios setup are all correct (disk id "0" as the boot disk, SCSI host-adapter bios installed, etc.), boot partition active, MBR freshly written, etc. Another SCSI disk with the ID set to "0" will boot fine! The disk can only be made bootable by low-level formatting from the scsi bios utility. After that it can be repartitioned, formatted and any operating system can be installed (OS/2, Linux, NT, W95, PC-DOS)and will boot. Before low-level formatting any of these OSes can be installed but none can be made to boot the machine. No data is lost on the disks except for the MBR or boot sector itself...(?). All of the machines involved have MoBos with onboard Adaptec ultrawide SCSI adapters (AIC 7880 = AHA2940UW) and have worked perfectly until this problem has arisen. One of the disks was a Fujitsu M2624FA SCSI II, one an IBM DORS and the 3rd an IBM DCAS UW. The third disk was subjected to operation for a short while without the SCSI bus being terminated or having term power. Could this really mess up the disk geometry so badly that the boot sector gets lost? None of the antivirus programs I have (IBM, McAfee, F-Prot) show the presence of a boot partition virus or any other virus. Can anyone make any suggestions as to what is happening. If you need more data feel free to write to me directly rather than to the list. I will respond to the list if I find out what is happening. Thanks again in advance, Bruce -- -------------------------------------------------------------------------------- Bruce Boschek - Institute of Medical Virology Justus-Liebig-University - Giessen, Germany Brought to you through IBM OS/2 Warp 4 and MR/2 ICE (Reg. #19501) ---------------------------------------------------------------------------------