Google Map widget display problem

Hi developers!

     I have a problem with the google map widget.

I have given some locations to the google map.

The first time I load the mashup is shows normally.

But after I navigate to other mashup, and return to this mashup, it becomes weird. Like this:

The strange thing is that I can still see the locations and the google logo, but the map can't display normally.

Could somebody help me out? I'm in a bit rush! Thanks!

Lee