@PhyrePhox:
nope, i've not been using the file explorer in any way to move anything around
@zeno:
well, now THATS interesting news :O. i'm gonna keep an eye on that. because i have been deleting images only with OSX.
anyway, i low-level formatted the card in windows now, and set CHDK up again fresh from the start. i took a ton of pics afterwards to "test" and so far everything is working fine. guess i'm just gonna import the pix with iPhoto and delete em in windows.
thanks a lot!