problem loading .iso via grub

[justincase]

Hi!
I have built an "emergency" usb thumdrive that holds various tools (as .iso) + hiren's boot cd booting via grub.

problem: when integrating stresslinux iso, it starts booting fine but during "Loading KIWI CD Boot System ..." it "failed to detect CD/DVD or USB drive" slepps for 120sec and goes into reboot.

Is it this check essential or could it be avoided for making my scenario working? Having a big thumbdrive and various "rescue .iso's" is so nice a solution for everyday IT work, I think it would be worth the effort...

thanks