<http://img401.imageshack.us/img401/2518/19274010hz4.jpg>

Palette sizes are forgotten after Photoshop CS4 restart! Can this be fixed?

Doesn't happen here. Have you checked "Remember Panel Locations"?

Why is your image so dark?

yes i checked "Remember Panel Locations" but it still happens.

i darkened the image to make the text stand out.

The behavior is normal. Palettes docked in the default right sidebar will always return to their default sizes while the layout engine tries to stretch them as evenly out to fill the entire height. If you are interested in retaining the sizes better, you need to float the stack and convert it into a user-defined "flotilla" (that's what Adobe calls them).

Mylenium

i think its more sensible to have it only auto stretch the bottom palette of the stack...

Well, that depends. As the swatches palette and others are "stretchable" as well, it will attempt to allocate available space evenly to each of them which makes sense, if e.g you are using a full Pantone swatch or something similarly crowded. If you still like it to behave differently, file a feature request:

<http://www.adobe.com/go/wish>

Mylenium