I've had the same problem running 1.6 on a G4 350mg Mac. In addition to that, I have no filter or advanced option tabs. I unistalled, re-downloaded and reinstalled 3 times--same problem. I had no such problem with 1.4B.
Also, I'm behind a firewall and with 1.4B about 60% of uploads were successful. With 1.6, it's about 10%. I assume this is because I can't configure the auto push request. Any help would be greatly appreciated, since I didn't save a copy of the 1.4B installer, and every link I find now has 1.6. Thanks!