Hi

I have been using WinXP and Ubuntu (initially Edubuntu 6.10) for the last few months with no problems.
The OS are on 2 separate disks.
Linux disk holds both Edubuntu 6.10 and the latest Ubuntu Feisty 7.04. They are on separate partitions.
When I installed Feisty I had planned to save the bootloader onto a USB key, and then copy the bootsector onto C:\ in Windows, but I didn't. Therefore GRUB took over WinXP boot.ini, although I could still boot into Windows.
I then decided to use fixmbr to re-establish WinXP booting, and tried to export GRUB bootsector onto C:\ with dd... command.
It didn't work. I could only boot into Edubuntu (which I had installed with bootloader on USB key as described above). Ubuntu only showed a series of 99 99 99 ..., when selected.
Now the problem is that, after I did all this, I cannot use both hard drives at the same time. They are not recognized by the BIOS. But if I remove Linux HD I can boot into WinXP.
I am about to try if BIOS can see my second HD.

Can this problem be caused by the process that I wrongly followed with Ubuntu installation? It could well be the HD, as it is a 26GB I used for at least the last 8 years.

I am going to try if it can be recognized by the BIOS when I disconnect the Win HD. In the mean time an experienced comment on this issue is very welcome.

Thanks
Giuseppe

exactly what command did you use here ?

It looks like the Linux HD is dead.
Not a sausage from it. BIOS cannot see it, whether it's configured as a Master or as a Slave or Cable Select.
All of this happened this morning when I turned the PC on, and discoverd that both HDs were not recognized by the BIOS.
Since then I tried recovering using PE Bart for WinXP.
And with that I managed to read Windows disk.
Then I disconnected Linux HD and realised I could boot.
Hmmm...Still investigating...

By memory:

dd if=/dev/hdb3 of=/ubuntu.bin bs=512 count=1

that command copies the first sector of the partition hdb3. This is commonly called the "boot sector". You always have to have boot code in the MBR if you are booting from any harddrive directly. The MBR is the first sector of the drive--not part of any partition.

depending on where you are in your trouble-shooting, the "booting" link below might help.

I have just done something that I had done and learned in the past from somewhere on the net.
The BIOS was in a sort of confused state.
I inverted the Lithium battery close to it for a few seconds (my MOBO does not have a jumper for the reset).
Resetting the BIOS chip means now that BIOS recognises the thought dead Linux HD.
I still have the problem that I cannot access Linux as the bootsector created for Windows doesn't work.

At least one problem is solved...

"bootsector created for Windows"
See my previous comment about the difference between MBR and bootsector. Most dual-boot setups would not do anything with bootsectors.

You can boot up from a live CD--eg your ubuntu 704 CD--and re-install GRUB from there. There's also a handy new thing out which I have been meaning to try---the "SuperGrub boot disk.

Thanks pixellany.
I realized the mistake.
Do you expect I can still boot into the Feisty even if i don't have GRUB any more on the main disk?
After all I don't have any importnt data in Ubuntu.
The only annoyance is that I had installed many games for the children, other interesting applications, Qt designer and other programming tools that I use quite a lot, and the downloading process was rather long (nearly 2G of stuff).
But, hey, I could start again and a avoid the trouble.
nless it is really easy to re-establish GRUB....

I like the though!!

It is really easy to install GRUB---it is also relatively easy to re-install Linux. Take your pick.

If you can get into any Linux (including live CD) you can get into your installed version.

I used Supergrub last night.
Unfortunately, although it said that the process of "re-creating" GRUB had succeded, it has actually installed
GRUB into the MBR of the 2nd disk where LINUX is.
My system MBR is on the 1st disk, where WinXP is.
Using another tool from SuperGrub I was able to boot into Ubuntu Feisty (even if it was on the 2nd disk) to confirm the above.
I still have to figure out how to manually create a file onto a floppy or USB key (like bootsect.lnx) that I can stick onto C:\ and insert a line in boot.ini (WinXP) to call the file and boot Ubuntu Feisty. (this was what I did with Edubuntu 6.04)
I still haven't gone throguh the reading. I'll do it tonight back from work...