The times when the map does work, fiddler shows the http image start downloading and then finish...
The times when the map does NOT work, fiddler does not show anything (no activity at all in fiddler)...
Also, another interesting observation: When there is only one of the services sub layers turned on, it seems to work every time, but if a few layers are turned on, that is when it is temperamental.
Thanks SharpGIS!