Log in as main user (or administrator) or chose "Run as administrator".
When starting up BricsCAD, a message box appears:
"Failed to update the system registry. Please try using REGEDIT".
Running BricsCAD requires access rights of at least the 'Main user' group because of registration of an OLE Server class in HKEY_CLASSES_ROOT.
Important note about Windows Vista and higher:
It is not sufficient to log in as administrator or main user, you also have to start BricsCAD by right-clicking the shortcut and choosing "Run as administrator".