I get the message, "Cannot explode AECC_POINT_GROUP" while doing random things in Civil 3D 2007.

For example, moving mtext, turning on/off layers, moving a polyline node.

This causing the whole program to freeze and i have to restart my computer.

So far it has happened 4 times in the past 20 minutes.

I have run recover and audit and this does not help.

Any help would be appreciated.