I now have a much more complete understanding of the problem, and it seems to be caused by the new chat feature that everyone loves so much
The problem started about 3 weeks ago, right at the same time I noted that the chat feature seems to keep turning itself back on all the time when using Sailnet from my computer. (See other thread
for that.) Suddenly Opera would not load the pages (see description above).
A few days ago I realized that I could load the pages as long as I turned off "mobile view" (in Opera Mini 4) or "single column view " (in Opera Mini 6). Today I discovered that the chat buttons were appearing in odd places on the page, often obscuring useful information that I wanted to read. If I clicked on any of the buttons (hoping to turn off this annoying feature), the page just reloaded without changing anything. Fortunately these buttons were not obscuring the "log off" link, so I clicked there. This also turns off the chat feature and eliminates the buttons altogether.
After logging off, I changed my settings back to mobile view/single column view, and SailNet works fine.
3 weeks ago I was able to use Sailnet on my phone in Opera Mini while logged on. So something changed on Sailnet's website, and it seems to be directly traceable to changes in the chat feature.
Yet one more reason to eliminate this annoying feature from Sailnet altogether.