I don't want to be picky but do need to be clear about something.
Grub is installed to your MBR, and for it to display your boot screen it reads files from whichever partition was used as its 'root' when it was installed.
In your case, you can see the boot options page and can make a selection, so Grub is actually functioning. You can boot Windows from the relevant Grub option, so all is OK there too.
17 : Cannot mount selected partition
This error is returned if the partition requested exists, but the
filesystem type cannot be recognized by GRUB.
Now you have four Linux partitions listed ... hdb1, hdb5, hdb6, hdb7 (hdb2 is the Extended container for hdb5, hdb6, hdb7)
hdb5 is the Swap partition, so that is identified correctly.
hdb1 is reported as Reiserfs and the other two as ext3.
From your boot menu it would appear that you are using Reiserfs for the root partition.
It appears Grub does not recognise it so a couple of suggestions .....
boot a live CD and do a file system check on that partition maybe using fsck.reiserfs
In view of the suspected events that caused this situation I also suggest you do a file system check on the other Linux partitions, also using fsck.
Having checked, and maybe repaired some of the partitions, it would be a good idea to check their UUID and edit the /boot/grub/menu.lst file to ensure it is using the correct UUIDs.
Then try to boot again from the HDD.
Of course if hdb1 is not your root partition of the Linux install then that would change things somewhat.
If you wish, when editing the menus.lst file on hdb1, you could change the UUIDs to the dev nodes of the partitions which should work also ....... /dev/hdb? ..... " ? " representing the partition number.
Hope that helps a bit.