Strange Compiz glitch

Noticed this before on my work machine which always had Compiz, but only now on my home setup where I’ve only just enabled Compiz. Every now and then, some mouse action (think it’s mousewheel scrolling, or some other action, haven’t been able to identify it yet) suddenly moves all applications from their workspaces to workspace 1.It’s an annoyance more than anything else but who wants to be annoyed?