I have made a lot of gifs, but sometimes, and I don't have a clue why, the gif file animation shows tiny white pixels. Like here:

I have a 24-Blog and as you can see I make a lot of gif-files. Can somebody help me avoiding this problem?
notes:
- the gif images are +/- 18kb (256 colours).
- when I put the gifs in a easy little program like 'UnFREEz 2.1' It works, good image quality, but of course I can't change the timer like I want, such as in Adobe ImageReady.
