The older version 5.0 of NanoCAD is abandonware but fully functional. It mimics AutoCAD 2004-2006 interface and can run from a USB stick with no activation.
To fix the issues with the AutoCAD 2005 portable version, follow these steps: autocad 2005 portable fix
There is a legitimate conversation around "fixing" AutoCAD 2005 to run on modern Windows—without cracking the license. This involves: The older version 5
If none of the above fixes work, try reinstalling Autocad 2005: autocad 2005 portable fix
and make sure it points to the current folder where your portable version lives. 5. Hardware Acceleration Crashes