Edit: I just tested my hack, and it worked fine for me when I tried the "Try for Baby" option in a photobooth instead of Woohoo. You could try updating the preg4all hack (if you use it) and see if that fixes your problem. *shrugs* If it doesn't, I'm not sure what else it might be. I wish I could interpret Error Logs better. Sorry this doesn't help.
This is a different error. That error (the one SIMplyLisa is referring to) has to do with a missing constant. That was because it was cloned from the InTeenimater, which had a reference to a BCON that I presume is specifically used for the InTeen mod.
This seems to be a "Stack number out of range" error. This probably means that it tried to reference something in an array or stack, but outside of the allocated size of that array or stack. In other words, the array may have a defined set of places for data, for example, maybe it holds 10 things, but the game tried to reference something greater than 10, and therefore it did not find anything.
Are you using any hacks related to Woohoo or Trying for Baby? I recently posted a mod on MTS2 regarding Risky Woohoo, and I would hate to think it is something I made.
Let me know ASAP. I better go do some testing of my own now...
Ste