After temporarily switching to another monitor, I've switched back to my 22" Iiyama, but the refresh rate seems to be locked at 60 Hz - and indeed this is what is displayed on the Monitors tab of the Advanced Display Properties. I can't seem to shift it off 60 Hz. Possibly relevant is that my Iiyama uses a BNC connector, not a D-Sub (the D-Sub is plugged in to another computer).
Any ideas?