Bridge PSD thumbnails pixelated

All PSD files thumbnails are appearing very pixelated in Bridge even after adjusting settings to following:

1. Preview Size: Monitor size

2. Preview Quality: High

3. Preview Generation: Always

I tried purging cache as well. 

Sagethumbs used to view thumnails perfectly sharp in Windows explorer, but my PC has been crashing recently so I am trying to avoid as much 3rd party apps as I can after I reset my PC yesterday.

Making above adjustments does not seem to make any difference on the thumnail quality at all.  Does any one know how to make thumbnails sharp & not pixelated?