I have spent 2 days searching the forum - homework done. I found many "related" postings but none which (1) were exactly the same or (2) provided a known fix.

Foe several months, KTorrent worked fine on UBUNTU Feisty. Suddenly when it was launched, a short "flash" of the opening panel appears and then nothing. Uninstalling and reinstalling do not help. If it is any help, the SAME EXACT PROBLEM now exists with Deluge.

I am trying to get away from Azureus. Any help? I am a newbie at this but a retired professional engineer.

Try to remove (or do a backup first) KTorrent config files:
~/.kde/share/apps/ktorrent
and
~/.kde/share/config/ktorrentrc
I had a similar problem with Amarok once and solved it by removing its config files.