DOSBox: whole screen turns black

[Philipp]

Hello,

I've installed DOSBox 0.74 from Ports on FreeBSD 8.2 STABLE. After starting DOSBox I get some weird graphical errors on the screen: short horizontal lines appear for less than a second, scattered on the whole screen. About 5 to 20 seconds later the screen turns black (dunno whether the monitor turns off) and after 2 seconds my desktop is back and it starts again.

My graphics card is an Intel GMA 3000 (Q965) with xf86-video-intel-2.7.1_4.

Any suggestions?

Philipp