A610, Fw: 1.00D, use the 1.00E version of SDM.
A620, Fw: 1.00F ( 1.00E is not compatible. You must upgrade to 1.00F)
S2 IS, Fw: 1.00L, use 1.00G version of SDM.
IXUS50/SD400, Fw: 1.01A may be updated to 101B using official Canon firmware available at Yahoo SDM Group.