1) Check your soft proof settings in [View > Proof Profile]
2) reprofile the monitor - the profile file itself may be corrupt or malformed in such a way that some programs (e.g. Preview/OSX) view it correctly but C1 views it incorrectly.
3) Reinstall C1 (delete the application support and preference files).
After updating to 6.4.3. Pro on a Mac running 10.6.8 the preview looks different to the outputted file. Preview is more contrasty and saturated than the output. Viewing everything on a hardware calibrated Eizo.
Thanks in advance for suggestions.