What is it that makes "text rescue" able to mount a drive, but I cannot mount it in a running system (or Knoppix/Ubuntu/CentOS Live CD etc) ?

When booting with "text rescue" it mounts the old filesystem and I can see all my data (Not that I can do anything with it.... I cannot seem to figure out how to get it out of the system????)

Anyhow I rebuilt a 2nd server, and tested and notice the same, even on a working systems I cannot mount the drives in another system....??

So, anyone able to help me either, mount the failed system (currantly sitting in the working system as hdc2) or mount it into anything else so I can copy some of the data off?

This all started with a Grub error 25 that I could not seem to fix...

Thanks for any tips.