PNG alpha not working after installing good NVidia driver (for OpenGL HW support)

PNG images used to work for me - the per pixel (RGBA) format was showing
variable transparency. However, after installing an NVidia driver:

for my

NVidia Quadro FX 330 graphics card
Intel P4 processor 3.0GHz (family 15, model 3)
Linux Fedora Cora 3 (2.6.9-1.667)

Now, there is just black where the transparency should be.

Please don’t reply with mention of a colorkey, the way someone did for an old
post regarding, apparently, the same issue. That has nothing to do with this.

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