Horrible pixelation and banding problem

[apocaalypso]

Hello,

I have a problem with scanning some Fuji Superia Xtra 400 negatives. I have Silverfast Ai Studio 8.5.0r7 on my Mac and a Plustek 8200i.
Everything has been fine until now, I tried to scan some negatives at 2400 dpi but the images came back very pixelated and with banding

Here is an example (look particularly in the sky) :
http://cl.ly/image/2b0l0y2Q190N

The settings I used :


How do you think this problem can be solved ?

Thank you!

[LSI_Ketelhohn]

'Dear customer,

Please make sure that you are using the latest driver.
To do so please
- remove all Plustek****.framework files from the directory /Library/Frameworks.
- Then reinstall the latest update again. It will install the latest driver.

Check if your scanner maybe is connected to the same power line as a fluorescent light or strong electrical motor.
These can create disturbances in the power line which in return can disturb the scanner.

Also disconnect any electrical gadgets or "toys" that are connected by USB (if present).

Make sure the scanner is connected directly to the USB port of the Mac.
Do not use a USB hub or extension.

Kind regards,
Arne Ketelhohn.