I have a similar problem with Nero 6.6 (latest Reload) and WB (latest beta - OD subscribed). I like to have the programs I use most frequently in my Quick Launch toolbar. Hence, I resize it to three rows* so that my taskbar also has space for taskbar buttons. After that I lock it. If I open Nero (at least Burning ROM or Express) it flattens my taskbar to two rows. In case I open it a second time it will flatten once again from two to one row. But opening more times after it is only a single row has no effect (so if you never resized and locked you taskbar you won't experience this). I noticed that this does not happen if the taskbar is not locked, but it looks too awful unlocked...
1GB RAM | Matrox Millennium G550 | Windows XP SP2 Pro All updates
* - With three rows the time/date will appear (for usual fonts) as
First Row: 15:45
Second Row: Monday
Third Row: 20/03/2005