Hi
1) Maybe you have set the grid tool... :-D
2) DPaint III (and older versions) doesn't work on AGA modes or graphic card. Your workbench (or public screen) must be in PAL or NTSC mode (no productivity, or multisync features) before start DPaint3. I have the same phenomena with Dpaint IV under picasso96.
3) With DPaintIV you can work with resolution and color# used before in DPaintIII (i.e. 32 colors 320x256 PAL) by selecting a compatible screen mode, at launch time, in the first panel. When you save your artwork, it will be compatible with what AMOS needs. :-)