This problem has been with me every since I started using WordPress w/ version 2.9 ; has persisted through upgrades since then.
If I've uploaded some pictures to a post, or if I go back to a published post to edit images in the Media Gallery, I am unable to rotate any of the images (e.g. 90 degrees to the right or left). The buttons for doing so are present but grayed out; if I do a mouseover, the following is displayed:
"Image rotation is not supported by your web host (function imagerotate() is missing)"
I'm able to reproduce this reliably and repeatedly.
I've installed the ImageMagick plugin for WordPress, but that has not seemed to make any difference.
My webhost is Hurricane Electric
It is running ImageMagick 6.3.7 06/04/09 Q16
Any ideas or recommendations?