Ubuntu 8.04 mit Firefox 3 = fatal combination !?

[SYNass IT Ubuntu / Linux]

Hello Ubuntu cracks
Promoting Ubuntu  I installed Ubuntu 8.04 Beta i386-ALT ! ;-)
Installation went smooth and without problems !! ;-))

Later we learnt that installing needed Firefox add-on's abended with
error 203 ...
... especially Foxmarks ...
... which means without Foxmark shared bookmarks cannet get to the
system and sync'ed . ;-O
This gives a very bad impression to the fellow involved !! ;-((

How do I get this done ???

TIA for assistance and hints.
Cheers svobi