I'm using XFCE 4.6.1 (Xubuntu distribution) on my laptop and main computer; the settings are approximately the same. so far for the intro.
What I'm experiencing is that when going to the screen edge over the task bar on the laptop, the button under the mouse is active. On the main machine however, having the mouse on the screen edge, the button below it doesn't react at all! Only if I move the pointer towards the center a bit, the hover highlight starts and the button becomes clickable.
I've tried to change the panel size, desktop theme and a few other settings, but none seems to cure that problem. Is there something that causes this problem? (Googling also seems to give no results)