I'm not a software developer, and as far as I can tell there is no information from Nero about this subject. Searching on Google took 2 minutes to see that everyone who has experienced the same issue, resolved it my upgrading Nero.
I'd guess it is because your using an older version of Nero (8) on Windows 7.
More info about Nero 8 and Win 7 compatibility:
"Nero 8 has not been tested to meet all of the technical requirements to be Compatible with Windows® 7. Nero 9 has passed Microsoft-designed tests for compatibility and reliability on PCs running the Windows® 7 operating system. Upgrade to Nero 9 today for Windows® 7 compatibility."
Link -
www.nero.com/enu/downloads-nero8-update.php