[sdiy] power supply question?

[gregory zifcak]

hello,

i am having trouble with what seems like a fairly simple circuit. it is the 
power supply for the x0xb0x ( 
http://ladyada.net/make/x0xb0x/fab/ps/index.html ).

all of the tests on that page check out correctly for me except the last 
one; where i should be getting 12v and 5.333v, i am getting 24v and 12v 
respectively. all of the components are the right value and oriented 
properly, and i've checked all the diodes, caps and resistors with my meter.

the schematic is here:

all my voltage readings from the junction of r1 and r2 over to ic23 seem to 
be twice as high as they should be.

any suggestions?

thanks in advance,
greg