Error unmounting drives after re-master.

I re-mastered KNoppix 3.2 for my upcoming Penguin Sleuth Kit project. Everything works fine so far except one thing. While in KDE if I mount a drive read-only, play with the explorer then try to unmount the drive I get an error that says

Code:

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could not unmount device error writing /etc/mtab.tmp

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Anyone know what that means and what causes it. My KNOPPIX CD that I remastered from works fine. I didn't change much to affect it. Any help would be appreciated...

Thanks,
Ernie