I am having the same issues with a new Pofung(baofeng) UV-B5 on both Windows 7 and MAC OS X Mavericks with CHIRP. The OEM software works fine on Win7 for me though. There is not MAC Version so I can't do much troubleshooting on it. CHIRP does work on the MAC with a Puxing 777 and a Kenwood TH-K2 successfully. Only the UV-B5 gives the error.