I've just updated beryl from 0.1.4 to 0.1.99.2 (Fedora Core 6, driver 1.0-9746 x86_64, Quadro FX 3450) and ran into a bug where all my windows appear white, and I can't do anything. I can still see my landscape and my cube, though.
(a report of this problem, not made by me)
(a similar issue, the other is apparently a dupe of this one)
The person who answered the bug report seems to think this is an Nvidia driver bug, which is why I'm posting here.
In any case, here is what I get when I run beryl and see those white windows :
beryl: pixmap 0x3e00103 can't be bound to texture
beryl: Couldn't bind redirected window 0x38009b2 to texture
beryl: pixmap 0x3e00105 can't be bound to texture
beryl: Couldn't bind redirected window 0x340007b to texture
[...many of those, with different 0x values...]
Then I hit Ctrl+C and see plenty of :
[IPCS]: Unable to change values during paint operations!
But since everything was white in the meantime, I don't know if those last messages are a result of killing beryl or if they where there before.
Running beryl with "Copy" as the "Rendering path" (i.e. the --use-copy option suggested in the bug report) does work around the issue, but does also slow down the entire desktop.