Playback pixilating everything

[braidlady]

I've been editing a video for a few weeks now and until 2 days ago, playback appeared as expected. Now when playback is activated for any part of the video, everything is pixelated: stills, title pages, videos, animations. I thought it might be caches or a need to reboot: didn't help. If I play the original videos or any other single element outside of PPro, they look fine.  Maybe it's some kind of setting issue, but I haven't changed any of them since everything was working. I don't know enough, to know what to try. Any thoughts.  

I use a custom designed for Photoshop-type work Maingear desktop, 64 bit OS (windows), x64 based processor;32GB, Intel, CPU @ 3.6GHz  

[Warren Heaton]

Check what you have the Playback Resolution set to.

This option lowers resolution to favor smooth playback.

[braidlady]

Good suggestion; but everything is at 1/2. Some things I did today even had the choice of a 1/4 but that didn't make a difference either. Thanks.