Mark,
okay, I have checked the source code.
The UNPACK library tries to create the output file using the CreateFile Windows API. This process returned INVALID_HANDLE_VALUE.
The UNPACK library returned the following to SetupBuilder:
return -200000000 - GetLastError();
Because you received Decompression Error -200000002, I can confirm that GetLastError was ERROR_FILE_NOT_FOUND
2 (0x2) The system cannot find the file specified.
The installer always tries to create the target folder (if it does not exist). Is your path "\users\username\documents\foldername" a fully qualified pathname?
Friedrich