Avatar Cropping Problems

I've searched these forums but can't find any current related topics.

We have now had a couple IE 8 users report trouble with the cropping of avatars. Among other things, they report that the crop tool appears off of the image and cannot be moved. (See attachment)

I've upgraded to the current version of the plugin and at least one user still reports trouble with the inability to crop an image, or a black avatar being created. In the past this has indicated an invalid file format, but this member insists they uploaded a jpeg and when they attempted to crop it, "the crop tool was off center" and resulted in the "blackout" avatar being created.

Another member found success with the Alternative Upload, but only with files that "Weren't too small or too big" ... apparently images smaller than 300px wide would cause the crop error. And large images created a black avatar.

<sigh>

Granted, our users are not technical, in the least. But we can't replicate this and I'm hoping someone here can provide direction as to where I can start troubleshooting the issue.

WPMU 2.9.2
Avatars v. 3.4
PHP v. 5.2.13
PHP Memory Limit: 500M
GD Library: 2.0.34