Downgrading my kernel to linux-image-2.6.31-02063113-generic makes this problem go away. (This is with X11 packages from the xorg-edgers PPA, but those shouldn't be necessary, since they never seemed to make a difference anyway.)
I believe this is technically a Karmic kernel---it's the most recent available mainline build of 2.6.31, from June 4---but have not noticed any anomalies from my Lucid system running on it. For those interested in this workaround, kernel packages are available here:
Downgrading my kernel to linux-image- 2.6.31- 02063113- generic makes this problem go away. (This is with X11 packages from the xorg-edgers PPA, but those shouldn't be necessary, since they never seemed to make a difference anyway.)
I believe this is technically a Karmic kernel---it's the most recent available mainline build of 2.6.31, from June 4---but have not noticed any anomalies from my Lucid system running on it. For those interested in this workaround, kernel packages are available here:
http:// kernel. ubuntu. com/~kernel- ppa/mainline/ v2.6.31. 13-karmic/