Ubuntu 10.04. Guest - dull and sluggish

[Trip Fontain]

Hi everybody.

I just installed Vbox 3.2.4 on MacBook3,1 / 2,2Ghz, 4 gig RAM. Host: Mac OSX SnowLeopard / Guest: Ubuntu 10.04.
Installation worked fine. Vbox-Guest-Additions are installed. Guest-System runs with 2G RAM / 128 MB Grafic-Memory / 3D-Accelaration activated / 2D-Accelaration not possible to activate.
Grafic-Drivers in Ubuntu are installed and in use, Resolution in Full-Screen-Mode = 1280x800. Anyway, the Guest-System behaves inactive and dull i.e. Windows move buckingly only and the login-melody sounds like a pitched down barrel organ. Any Help?