Why isn't Helvetica Neue rendering properly?

I installed some new Helvetica variations the other day and since then Helvetica Neue isn't rendering how it should (in Chrome or Firefox).

I tried deleting all the Helvetica fonts and installing them again but they're still not rendering properly.

This is what it looks like:

Some letters appear to be taller than others?

The font should be: normal 14px/1.4 "Helvetica Neue","HelveticaNeue",Helvetica,Arial,sans-serif;