OpenGL not working (Arch Linux)

i installed Arch in VirtualBox on win7.
every thing is working fine except OpenGL
whenever desktop effects is acvited by OpenGL video gets corrupted

display manager : KDE4

# uname -a
Linux myhost 2.6.38-ARCH #1 SMP PREEMPT Fri May 13 07:54:18 UTC 2011 i686 Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz GenuineIntel GNU/Linux

# lspci -v

00:02.0 VGA compatible controller: InnoTek Systemberatung GmbH VirtualBox Graphics Adapter (prog-if 00 [VGA controller])
Flags: bus master, fast devsel, latency 64, IRQ 18
Memory at e0000000 (32-bit, prefetchable) [size=128M]
Expansion ROM at <unassigned> [disabled]

00:04.0 System peripheral: InnoTek Systemberatung GmbH VirtualBox Guest Service
Flags: bus master, fast devsel, latency 0, IRQ 20
I/O ports at d020
Memory at f0400000 (32-bit, non-prefetchable) [size=4M]
Memory at f0800000 (32-bit, prefetchable) [size=16K]
Kernel modules: vboxguest

nobody faced this problem with arch ??

As far as I know, desktop effects are not supported by VirtualBox.. but, I can be wrong coz I never tried to activate desktop effects.. But I did try to enable Aero in Win 7 under VB but that wasn't success..

ok. that might be the case.

still i will keep looking.