I am working in Illustrator (15.0.2 (CS5) or 16.0.0 (CS6)) and when I try to move objects small distances, they snap to the nearest two pixels on some invisible grid. I can't find anything in the preferences. Here are some screen shots:
For new objects, turn off "Align to Pixel Grid" on the Transform panel.
For existing objects, select them first, then turn off Align to Pixel Grid using the checkbox at bottom of Transform panel.
It was driving me crazy too... you can deselect the
Align to Pixel Grid checkbox on the Transform panel (shows up on "show options"), but new objects will always retain the snapping behaviour.
To turn it of permanently, click on the flyout menu at the top right of the transform panel then uncheck
Align new objects to pixel grid.
THIS HAS BEEN UPDATED IN VERSION 23.0.1 You have to turn OFF "snap to grid" behavior. The preferences for alignment of objects are in three DIFFERENT places:
This has finally been updated by Adobe in the latest version of Illustrator v.23.01 and later.
In Illustrator 2019, the snap-to-pixel toggle has been moved to a more convenient location in the top right of the application. It is the magnet icon connected to three vertical squares.
Clicking it toggles snap-to-pixel and the dropdown arrow to its right opens an advanced options menu with additional settings.