I have booted grml iso but my grub2 is on hd and no grub2 usb stick
2) however your entry shows a gremlin gz at end of menu ....remove it pls
my link shows findiso not find_iso
3) I would like you to go back to grub2 menu boot stage and press C for commands and then type and enter.....ls
ls will show you what the (hdx,y) grub2 finds....including any fd0....if it finds hd0,x and hd1,x....hopefully your hd differs from usb and you should be able to instantly tell which is which.
4) staying at command mode I would like to share you to benefit of using TAB key to autocomplete the pathways but not to be used for isofrom or findiso
loopback loop (hd1,2)/i.....and press TAB key to autocomplete isos
if that fails you need hd0,2....assuming isos is a sub-folder on second partition
but theres more....
if usb boots normally what is fstab for this isos area?
eg /dev/sdb2 (or sda2) /isos....means you have created a structure where
is a non-LHS folder created using root powers and so you drop /isos from your pathway
in other words if the mount point for second usb partition is /isos/
your pathway in grub2 speak is actually
loopback loop (hd1,2)/grml-small_2008.11.iso or
loopback loop (hd0,2)/grml-small_2008.11.iso
edit so I suspect at command mode you may succeed with
loopback loop (hd0,2)/gr......and press the tab key