Qt 4.6.2 Assistant fails to display

Upgrading Linux Ubuntu 9.10 to 10.04 included an upgrade of Qt from 4.5.2 to 4.6.2. Running assistant from the new distribution displayed the GUI, the documentation index was generated, and the application worked fine. Starting assistant a second time the GUI flashed very briefly on the screen before disappearing, but the process remained running (it had to be killed). Thinking the problem might be with the Ubuntu upgrade distribution I downloaded a fresh qt-sdk-linux-x86_64-opensource-2010.02.bin distribution, installed it in a temporary location, and ran assistant from there. Same problem: GUI flash then nothing and process left running in limbo. I have a 4.5.2 distribution (qt-sdk-linux-x86_64-opensource-2009.03.1.bin) from which assistant continues to run just fine.

What's the problem with the Qt 4.6.2 assistant and how can it be fixed?

Thnx.

Addendum:

The Qt assistant window did not appear because it repositioned itself off the display!

I am using the Enlightenment (e16 v1.0.0) window manager. When I use KDE the assistant application appears correctly and reappears at the same location each time it is restarted. By moving the location of assistant far to the right in the display while using KDE, then changing to e16, assistant will appear at the same location when started the first time. But on subsequent starts it appears far to the left of it's previous position (so if it had been near the left edge on last use it is repositioned off the display when restarted). However, if the application is moved any amount (no matter how small), it will reappear at that location when restarted.

Non-Qt application do not have this issue.