Right, as I'm now using the current version 3.93 I assume that it's all right to post this - especially as it's registered and paid for?
When I did a search on the Radar Contact forum for "FSUIPC_WAIT" I found eight threads, excluding my own, relating to this issue going back to 2006. In five of those the response from John Dekker was to ask which version of FSUIPC was being used and if it wasn't the latest he advised going to that. The implication here is that he believes FSUIPC is the key to this problem. Also, a respondent to my post said he had believed this problem had been solved as it hadn't happened to him for a long time but he had just gone to FSUIPC 3.93 and it had then happened on his next two flights.
So forgive me if I got the impression that FSUIPC was regarded as the culprit but I think many people reading what I had read would think the same.
After all this I still do not have a means of solving this problem - the suggestions made in response to my post didn't work. Others seem to be able to ok the message and RC carries on. Not in my case as the message keeps coming back - unless I've got to be a bit more patient and keep ok-ing until I've cleared a backlog?
Anyway, don't you worry about it Mr Dowson - after all, it's only Flight Simulator.
Iain Smith