A macro is simply a programming script that automates software functions to speed applications. When opening the TNT®, you should expect to see this dialogue box open prior to the TNT® loading:

This is completely normal, simply select "Enable Macros" with your mouse. NOTE – For Microsoft Excel 2007 (Vista edition), this will be different.

After Selecting Options in Excel 2007, select “enable content” and “OK”
Demystifying Macros Excel 97 through 2007 – a simple video:
If you see this message in Excel versions 97 through 2003:

Then Excel has been installed on your machine with a high security setting. To change this, follow these steps:
1) Close the TNT® file.
2) From the tools menu in Excel, select “Macros”, then select “Security”, select “medium” from the list. Save these settings by clicking “OK”. You are now ready to RE-OPEN and use the TNT®.