Unwanted lines on semi transparent object drawn with pen tool

[Violet26213002v0mw]

Hi everyone,

I am getting unwanted lines on the edge of a shape that I have drawn using the pen tool.

The lines only appear when I bring down the opacity of the shape (to make it semi transparent) and seem to follow the adjustment handles of the anchor points – I believe this must be somehow creating the problem.

I've changed the opacity and colour various times but the problem persists. Please see photos. 

Please could someone advise me on how to get rid of these lines.

[Monika Gause · Accepted solution]

Please try View > Preview on CPU.

Better?

[Violet26213002v0mw]

Yes! Thank you. Would you mind explaining what was causing that to happen? 

[Doug A Roberts]

Bugs in the GPU preview.

[Monika Gause]

The GPU preview (based on your graphic card processor) is lightning fast, but not precise. The engineers try to hunt down some issues, but actually it's futile, since every update to the graphic card driver will introduce new one or render the things they fix useless.