Right... I found the problem. I had adjusted the ro.sf.lcd_density from 240 to 180. This is found in \System\build.prop and gives the impression of an increased screen resolution, just as found in some CyanogenMod builds that I used before for my HTC HD2.
Anyway, when I changed it back to 240 and rebooted, Contacts worked fine. I'm not sure why the contacts app requires this lcd density. If anyone knows why this happens I'd love a suggestion to get it back to 180, as it looks better.