I think the partition type in the partition table for 4th entry is corrupted. See if following can help..

Mount the disk on secondary, boot from another hard disk having linux and then use cfdisk/fdisk and change the partition type for hda4 as "05" which means extended. Write the partition table back, quit and check if now your logical partitions are visible.

Another way to debug is write a simple program to dump the MBR partition table i.e. 0x01be - 0x01fd from the first sector on the disk, then read the starting sector of the 4th entry and dump the partition table in that sector. See if you have any entries for your linux there. Modify the MBR partition accordingly to reflect.

HTH,

-Mayuresh

If memory serves me right, On Nov 28, anand wrote :

a:I was trying to load a new OS. a:I had linux partitions in hda5 and hda7. a:After the OS loaded, i tried to run linux rescue from pcq linux 7.1 (linux CD from PCQ which I use as my OS). a:I could not rescue using standard method. a:Next Itried to upgrade it and I found that I could not upgrade and was getting this error a: a:An error occured reading the partition table for the block device hda. The error has logical partition of type 0 detected. a: a:then there was some such explainatory mesage. a:On saying Ok, it skipped the disk. a:Then i loaded another hard disk and I can now see that the hard disk shows hda4 which has size equal to the addition of sizes of hda5 and hda7. a:but it does not show hda5 and 7 in brackets. a: a:How do i retrieve my old data. there is almost twenty days of un backed up data or rather data backed up on hda7. a: a:Any clues to this problems solution? a: a:Anand a: a: a:_______________________________________________ a:http://mm.ilug-bom.org.in/mailman/listinfo/linuxers a: