I apologize for the triple post and bump, but I wanted to give this a follow up just in case others were having issues too.
I eventually identified and fixed the problem. It seems that my game controller (a dualshock3) had a duplicate entry under the Device Manager. The duplicate entry was still using an older version of the driver. So I just disabled the older one and Dolphin worked as expected. Older revisions seemed to work fine with the duplicate entry enabled, so I never suspected it.
Not sure if this would be considered a user error then. If you'd like more information (perhaps on the drivers that are being used) feel free to ask. If not, feel free to ignore.
I eventually identified and fixed the problem. It seems that my game controller (a dualshock3) had a duplicate entry under the Device Manager. The duplicate entry was still using an older version of the driver. So I just disabled the older one and Dolphin worked as expected. Older revisions seemed to work fine with the duplicate entry enabled, so I never suspected it.
Not sure if this would be considered a user error then. If you'd like more information (perhaps on the drivers that are being used) feel free to ask. If not, feel free to ignore.