Mac Pro 1,1 crashes, strange lines, Hold power button

Hi Everybody,

My Mac Pro 1,1 keep crashing since a day or two.

Sometimes I get an error message, see pictures below. And sometimes I get the message: 'You need to restart your computer, hold the power button until it turns off..'

When it freezes, everything on my screen shows small en larger pink lines.

And sometimes it shows bigger lines on top of my screen, see last picture.

When it freezes I can still move the spinnig beach ball, but it has a little square around it in black stripes.

A few moments later the beachball also freezes and my Mac is completely frozen.

I performed an Apple Hardware Test, but it shows no problems.

See the pictures below, thanks for reading.

Bart, the Netherlands.