What's a ".sh" file?
Sounds like you need to give a bit more detail. I can't tell what program it is that refuses an invalid MD5 sum.
Are you actually running a file that ends in ".sh"? If so, it sounds like a shell script, and you have to look through the script itself to see where it barfs on an invalid MD5.
If you are running rpm, then you can try "rpm --nomd5". I don't know if that works for installing, or just for verifying.
I see you use Mandrake 10; you might be installing from the graphical interface (rpmdrake). You might want to switch to a console and run "rpm --nomd5 -i [package name]" as root. (Not sure about command syntax --check with someone else.) Even the more user-friendly "urpmi" command doesn't give an option to ignore md5.