David,

This same problem occurred with Maple 11 in some instances.  It is some problem with how Java handles the amount of memory on Windows machines.  The way to work around and correct this is:

Open the launch.ini file using a text editor(On typical installation, it is found at c:\program files\maple 12\bin.win\launch.ini)

Towards the bottom of the file, there are 2 lines:

# set maximum Java heap size

# maxheap=700m

On the second line, remove the # and the space to where it looks like the following:

# set maximum Java heap size

maxheap=700m

Then save the file.  I had this in a lab environment and saved the file to a flash drive for distribution, replacing the ini file on all systems in the lab.  It has worked 100% for me.

Mike