tabs don't load if an https side is involved

[LAZA]

Binary package hint: firefox-3.0

I have an bookmark folder with all important sides I check frequently (8 sites).
Normally I go to the folder, down the side and click 'open all in tabs'.
The first site on the bookmark is encrypted (https://www.arcor.de/login/login.jsp) so there apears then a window who warns me 'You are enterin an encrypted site'.
That's all correct - but only 6 sites where opened!

If I don't confirm the warning about the encrypted site nothing happens, the other tabs hang and act if they waiting also for the confirmation!
The other 2 sites don't open actually!

Normally should all the sites be loaded and only the arcor-site wait for the confirmation.

Ubuntu 9.04
Kernel 2.6.28-13-generic

ProblemType: Bug
Architecture: amd64
DistroRelease: Ubuntu 9.04
Package: firefox-3.0 3.0.11+build2+nobinonly-0ubuntu0.9.04.1
ProcEnviron:
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: firefox-3.0
Uname: Linux 2.6.28-13-generic x86_64