When I open my NEF files in ACR it says they are much higher resolution than they really are: 6144 x 4113. Then when I open them to edit in CS3 that size is carried over. ACR thinks my sensor is 25 mp!
But when I open them in Lightroom they are correctly sized: 3872 x 2592, and that size is carried over into CS3 when I open them in CS3 from LR.
This behavior started with a fairly recent ACR update -- I'm not sure exactly when.
This is in Windows, latest version of RAW, CS3, LR.