This recently started happening to me.
Photoshop CC 2014.2.2
Camera Raw v184.108.40.2064
I've cleared out my %temp% folder.
Shy of uninstall/reinstall, is there a way to fix this.
Bridge sees the preview fine and file opens correctly after this step just fine but no preview while adjusting.
disabling graphics processor from Edit>Preferences>Camera Raw Fixed the issue. Thanks!