Does it work with a different font? How about a plain old line you've drawn? I suspect the font did something funky when it was converted to outlines. Try a different font, see if it works, if it does, then the font is the culprit. I've done the effects you're referencing numerous times and no, I haven't seen that.
Last time I have used this font to create outline too, there is no problem there.
But start from yesterday, I face the same problem to all font type.
I suspect is there any setting in illustrator have change...(Maybe I accidently change it)
But I have no idea for which setting is related to it...
Well, without more info, I'm really not sure. What version of AI? OS/CPU/System/RAM? Do you use a font suitcase or similar app? What else is running? List the exact steps you are taking. Have you checked the Adobe site, forums, or help?
Is using Adobe Illustrator CS6, the same case happen even after I restart my computer and just open Illustrator to try it (without running other apps). I just type the wording, then create outline, and create offset path, then this situation happen. These steps are just same as what I've done usually.
Processor: Intel(R) Core (TM)i5-2300CPU@ 2.80ghZ
System Type: 64-bit OS