Since I could access the data using the URL either directly from a browser and also by clicking the link to go there in the PropView configuration (prediction), without any error - and - since the data source could be accessed in identical ways after the problem disappeared and appeared to look the same as before, I might conclude that it was not a hardware/software or internet service provider issue (especially since there were no other internet access issues). This would lead me to think it could have been a data source issue except that nobody else reported the problem on this site recently as far as I can tell. So I guess it shall remain just one of those mysteries.
