Did MRU-Blaster erase register keys?

I started using MRU-Blaster last month. Now I wonder whether the program erased a register subkey my new MS Encarta is looking for during installation.
I can't install my new Encarta 2004 Reference Library. During installation the following error message appears:
"Could not open HKEY_Current .User\ Software\ Microsoft\ Windows\ CurrentVersion\Explorer\Discardable\PostSetup\....{00211493-000-000-C0000000000046}
Verify that you have sufficient access to that key or contact your support personal"
I use Win ME and when I tried to drill down to this register key with the Norton editor, it stopped at the\Software level, where I read the final entries:
name "ab (default value)
date "value not set"
BTW, I uninstalled the previously used Encarta 2003 before undertaking the Encarta 2004 install and when I tried to re-install the 2003 version, it too stopped with the same error message!
Any help will be appreciated.