Error 31048 is all over the bug report forums. The problem that I have with this is that it is fundamentally unfair to leave the AH active while a significant number of players are unable to use it. This creates a scenario in which only those who are able to use the AH can participate in the economy, which gives them a distinct advantage when buying.
Blizzard, please take the AH completely offline while you fix this problem. It is simply wrong to allow some players to continue to access the economy, while buggy software prevents others from participating.
Links to bug report threads: