Update on 02/26/14: There's a new version of Chrome (version 33), so this should be working now!
Some Pinners on the newest version of Chrome (version 32) are having trouble with the dropdown menu and category menu on Pinterest. We're sorry to hear you're having this issue! We've tested the newer version of the browser and believe this issue will be fixed in the next update to Chrome.
We appreciate your patience in the meantime!