Last question first - I think this has been caused by some sort of event which has broken several parts of your installation and is causing all these problems, rather than this is the root of all those problems. This is why I recommend a clean uninstall - full uninstall; thorough cleanup; reinstall without Anti-Virus or background programs running - rather than slapping a field dressing (RegFix) on the wound.
When some key registry values are damaged, the program alarms and gives you that error message. Roxio's RegFix file replaced only the values which were causing the alarm and not the root cause of their being broken. Perhaps that's why Roxio only issued RegFix files for only two versions of Creator?
In any event, I made a RegFix for Paul's NXT 2 under 64-bit Windows 7 and it worked under test on my machine, but we didn't get to test it in the field because he did the full uninstall; thorough cleanup; reinstall and it fixed the problem. Should you wish to try the quick, temporary fix, here it is.
I'm afraid the Community Forum Software by IP.Board 3.4.8 is playing up again at the moment and we can't upload the file to you here. I'll type it in and tell you how to make it work. NOTE: This for Creator NXT 2 under Windows x64 only.
- - - - -
Windows Registry Editor Version 5.00
- - - -
Highlight the bold text between the dotted lines
CUT [ctrl-x] or COPY [ctrl-c] the highlighted text
Open a word processor such as Notepad
PASTE [ctrl-v] the text into the word processor
Save the text as a file such as RegFix.reg to your desktop or somewhere you can find it.
To use the regfix file you've created, double-left-click it and answer yes or allow to the Windows questions. Reboot the machine to restart Windows. This should have replaced those 'Critical Registry Values', but I still recommend the clkuean uninstall/reinstall.