I have the same issue on a U2410 with the early 2011 MacBook Pro.
Although my U2410 does not go into PSM, it just blacks out when connected via DVI... I have two U2410's, one shows picture sometimes, the other has never shown a picture. Both are Rev A05 U2410's bought Jan of 2011.
Tested via DisplayPort and works perfect (so far).
Tested this with a older Dell 24" (1920x1200@60Hz) no issues via DVI Tested with other monitors with various resolutionss, no issues with DVI.
This is a Dell U2410 problem... Called Dell says call Apple... Call Apple, Apple says call Dell.