I just experienced the contrary.
I installed Ubuntu 11.04 Beta 2 and just after, tried successfully Sweet Home 3D version coming with the installer. Then I tried the version in Ubuntu Software Center and it didn't run at all.
As Ubuntu 11.04 is still in Beta stage, I would report an error log to Ubuntu team, and use a stable Ubuntu version.
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Emmanuel Puybaret, Sweet Home 3D creator
