Like Christoper said, contact Maplesoft Customer Support and they can handle your request for a new download and activation code.

You can find their email address and phone number on the Maplesoft Support page: http://www.maplesoft.com/support/

You have to email the Customer Support team with your Student number, school, and purchase code for them to confirm your student status. You may reach them at: custservice@maplesoft.com

If you contact Maplesoft Customer Support, (http://www.maplesoft.com/support/) they will be able to assist you in obtaining a new downloadable copy.

Note: Be aware that Maple 12 is not supported in Windows 7 and above.

I am not sure of what your original program is, but if you want to ignore the imaginary domain values, you may set the worksheet to only work in the real domain by using the line:

with(RealDomain):

Just be warned that you have to use restart; to reset the worksheet to include complex values after you are finished.

Are you sure that the .mapleinit file is in your home folder and has something in it?

By default, Ubuntu will hide files with a dot in front, so you have to press Ctrl-H to unhide the file in the file explorer Nautilus, then double check that it does have the required settings saved inside.

You can view a video on how to find an orthonormal basis for a set of vectors complete with worksheet here: 

http://www.mapleprimes.com/posts/7184-OrthogonalOrthonormal-Bases

There is a YouTube version here if the Quicktime video isn't working for you: http://www.youtube.com/watch?v=Mg817y_lC6I