with 256.44 displays exhibit trouble reviving from sleep

[etherfish]

I have a Quadro 1800 connected to two SUN X7200A (Apparently rebranded NEC 2070NX) connected to the two displayports with passive displayport to DVI adapters. This combination has worked well in the past. The machine was recently upgraded to 256.44 and, now, after xlock (mode blank) engages and the backlights are shut off via dpms (dpms standby), the displays are very 'hard' to revive. If I press letters and click repeatedly so that I am registering activity, the displays flicker on and off showing one of a number of things: "DVI-D no signal" box from the LCD, completely black with the backlight enabled, or brief flashes of magenta. Eventually, after 7 to 80 seconds of excitement, the displays will become coherent.

Logging in remotely and, as root, executing chvt 1 then chvt 7 will immediately return the displays to operation.

Unfortunately, I upgraded nvidia drivers, xorg, xlock, and the rest of the system in one fell swoop so I'm not entirely sure it's an nvidia problem.

Any advice?