@mpedant glad it's working!  It's had a few positive results on the Macrumors forums as well so it looks like we may have found it :)

To simplify the link I posted: download NVinject from here: http://support.crsltd.com/FileManagement/Download/829619657b484700ab7e57de5b88a481
and type into Terminal (from the download location)
sudo cp -R NVinject.kext /System/Library/Extensions/
and reboot.

Once it became clear that a dithering conflict was the most likely issue it was just a matter of putting "disable dithering os x" into Google.  Good team effort between us, other threads, whoever came up with the bits and pieces in those links and my Googling skillz ;)

@Cloudane yeah good googling.  I tried "Dell 2311H os x corduroy" which wasn't quite so effective ;)  Shame Dell weren't able to offer a bit more help, but a good result all the same.

@wojowork yup those stripes are history!

Well I have the new cable but the same disappointment. Just to confirm I have a macbook pro (2009) running OS X 10.6.5, using an Apple Mini DisplayPort to DVI adapter I get the corduroy effect, if I use a StarTech 6ft Mini DisplayPort to DisplayPort adapter cable I get same effect.  Got nothing against corduroy, but it doesn't make the screen much fun to look at for long periods of time.  Using a NEET Mini DisplayPort to VGA adapter I get no really noticeable pinstripe but it does look a bit shimmering to me (could just be my eyes), and the picture is not as sharp.  

Looks like nvinject doesnt work in 64 bit mode any advice?

12/15/10 7:57:08 PM com.apple.kextcache[307] /System/Library/Extensions/NVinject.kext doesn't support architecture x86_64; omitting from prelinked kernel.

switched back to arch=i386 seems like there are no real downsides ,  stripes are gone! 

Hey guys, it seems that I as well get the pinstriping problem on my early 2008 Macbook Pro with Dell U2311H. I can see it on certain contrast/brightness levels only though, while on others it's fine.

I would still like to remove the pinstriping, but I'm not so sure what exactly am I supposed to do. I checked the link Cloudane posted, but I'd need some guidance here. 

1. The "NVinject" file that I downloaded from that site is named "829619657b484700ab7e57de5b88a481" and it doesn't have any extension. Is this right?

2. Am I supposed to copy it to System/Library/Extensions/ and then run the Terminal command: sudo cp -R NVinject.kext /System/Library/Extensions/ ?

What if I wanted to undo the command or remove this command? How to do it?

Thanks in advance!

its a zip file, you have to unzip it first... :)  

Oh, turns out that I shouldn't have used SpeedDownload to download it. When I downloaded it regularly, it indeed was a zip file. Ok now that I have the "NVinject.kext" file, where am I supposed to place it?

The "cp -R" command copies the file from wherever you downloaded it, to /System/Library/Extensions

You may be able to copy it there using the Finder instead, depending on permissions.

Ok, so what if I didn't want to use it anymore - how to remove or undo this command?

Remove it with:

sudo rm -rf /System/Library/Extensions/NVinject.kext

And rebuild the kext cache using Kext Helper from cheetha.net/

Thanks for your input! I apologize for all these questions, it's just that I'm pretty much a n00b when it comes to these terminal commands and I really wouldn't want to mess my system up...

Just one more question: what do you mean to "rebuild the kext cache"?

All you really need to do is copy and paste the file to that path and run kext utility from  http://www.insanelymac.com/forum/index.php?showtopic=140647 to repair permissions and  then reboot.  Its not rocket science.  To my knowledge you can't break anything doing that :) 

I see. Thanks guys!

One more thing before I run it: once I've run the command and rebooted, will it only work until the next reboot?