Error in Map 3D 2011: Unable to plot a drawing

I have AutoCAD Map 3D 2011 and every time I am trying to plot a drawing, the error “You cannot use multiple instance of program at the same time” appeared.
And then Map 3D will freezes for a short moment and when it came back the plot was canceled.
I also have AutoCAD 2012 but I already tried to remove it ever since I got this error, but unluckily it doesn’t fix the issue.
The background plot is set to 1.
Need help! Thanks.

