I had a weird issue on a few clients sites where by the buttons under the ‘Upload/Insert’ were gone. I also couldn’t switch between Visual and HTML mode.
Thankfully I was able to pin point the issue was an old version of ‘Picasa Express x 2’ which I use to pull images in from Picasa. Great plugin by the way! Turns out I had updated a few client sites and hadn’t updated the Picasa plugin.
A simple click and all was fixed.
In my experience I always do the following:
1) Upload a completely new version of WordPress making sure you back everything up first. You only really need to update the root folder (minus the config file), plus wp-admin and wp-includes.
2) Be sure not to over right your wp-content file! This has all your themes and plugins in it!
3) Once you’ve updated and if you still have issues, try updating all the plugins you use.
4) If you still have issues, try turning of plugins one by one until you find the culprit.
99% of the time I follow this formula and it works. I hope that helps anybody else who has the same issue.