Screen goes shredded sometimes in Ubuntu 11.04

[imcampos]

I just upgraded to Ubuntu 11.04, everything so far looks fine, but twice the screen looked shredded and when I clicked Esc it started to blink sort of erratically.

My laptop is an oldie, an HP Pavillion dv4000, but it worked perfectly in 10.04.

Is this a driver issue? If yes, how do I find and install the right driver?

[stoneguy]

Some of those Pavilions (I have a minitower) have the problematic Intel video chips. Try nomodeset as explained in http://ubuntuforums.org/showthread.php?t=1613132