I'm going to assume you're on XP. Most of the following should apply to Vista as well. At any rate, it may help someone who comes across this thread.
Nero and RecordNow have been known to cause conflicts. This may no longer be true, but I had the same problem a few years ago and discovered it was (is?) a common issue when doing a search. In the end, I had to uninstall both programs and manually delete references to Nero (Ahead) from the registry.
There is a tool available at the Ahead website site called NeroCleanTool. Probably developed as a response to complaints/support requests. Uninstall Nero and run the tool. Uninstall the others as well. Run CCleaner (free) on the registry and back up when prompted, Google for it. Then pick ONE program and re-install. Immediately update Nero or RN's PXEngine, whichever you chose. (Personally, I use RecordNow and shun Nero. The last version of Nero that was good was v.5.5, IMHO.)
There's a further complication. You probably installed Nero's InCD, a packet-writing soft which lets you use your burner like a floppy, drag & drop. Packet-writing software is problematic, some folks have no real difficulties, but it's a crapshoot. BTW, XP's inbuilt burning is Roxio-based. Roxio and Nero are also known to conflict. If you insist on using InCD, it would probably be wise to disable IMAPI CD Burning COM Service in Administrative Tools -> Services.
Good luck.
