... only for the thing to stall immediately after the quick download test - 5% through before freezing.
So back to square one 
Try ticking the "Detailed Output" and "Port 80" boxes- it worked on a Mac.
Bill - I always tick the detailed output box anyway. I have also tried ticking the 'Port 80' box for these tests given the problems but it makes no difference either way.
All very odd since I have run the test without any issues for years on all my machines, whether Windows based or Mac.
Further update - I have now managed to successfully carry out 3 tests on my Windows 7 PC - admittedly using wifi connection only. I can't do an ethernet connection as my PC is in my office in the converted loft and the master socket is two floors down in the hallway. However the important thing is that the test now works. I will try using my Mac laptop this afternoon hard wired and see if I can get results from that.
However even allowing for the reduction due to using wifi two floors up my download is reported at 34Mbps and upload at 13Mbps. Using BT Whoesale Tester (also wifi only) I get 51.92 Mbps down and 14.13 Mbps upload. Profiles set at 77.43 down and 20 up. The BT test was done using an alternative network with the repeater being located in the loft. Shows the value of having the airport express