Howling:Gallifrey time-locked?

It's been stated several times in the New Series that Gallifrey and the Time War are time-locked, making it impossible to time-travel back to them. But then how were the War Lords' people in "The War Games", the Sontarans in "The Invasion of Time", and the Sleepers in "The Trial of a Time Lord" able to travel to Gallifrey. They would've come from different points throughout time, and weren't bound to Gallifrey's present like the Doctor's TARDIS. The Daleks also appear to be (mostly) unable to travel into their own past, as seen with Dalek Caan's ordeal. EJA 16:46, April 7, 2011 (UTC)