In the recent DW novel Prisoner of the Daleks the Tenth Doctor has a run-in with some Daleks that are said to be from before the Time War; I believe it's stated by the Doctor that this shouldn't be possible due to the time-lock placed around the War, which would normally prevent any interaction with the Daleks prior to or during their conflict with Gallifrey. Frankly, I find this idea a bit confusing, as throughout the new series the Doctor has visited time zones in which the Daleks must have been active.