Help - Cannot get SB4 & ASX PC to connect to FSX PMDG744 PC

I have been flying without problems for many months. Now, suddenly, I cannot get SB4/ASX to connect to FSX.My main suspect is the change from PC Tools to Microsoft firewall. But turning off the Windows firewall makes no difference.On FSX PC, my PMDG B744 is flying correctly. WideClient on my SB4/ASX PC shows it is connected to FSX.When I start SB4, I get a blank SB4 window except for 'Connected to 88.198.19.202 as BAV17V/B744' displayed. Initially when starting VAT-Spy, the flight window shows GS and Heading both as zero, ETA and Alt as blank. My position on the map is shown as Lat 0, Lon 0. Similar from ServInfo. Then, after a couple of minutes, the VATSIM server removes my flight details, presumably because of corrupt flight details.When I start ASX, the program initialises correctly, but then, instead of displaying the usual blue-bordered window, displays nothing at all. The task bar shows ASX is a running task, but there is no function to mouse clicks 1 or 2 on the task. The only way of stopping ASX is via the Windows Task Manager. ASX does not display the blue/green message strip on the FSX window.I now do not have any ideas what to do next. Anyone with any ideas, please?Cheers, Richard