# Something is wrong with “Information”

When a new session of kernel is started, searching for help with "?" question mark in notebook goes well, for example

But after some time, it becomes

I have no idea what I did that caused this problem. This situation occurred several times after using the notebook extensively. I think some commands triggered this problem. I'm using Mathematica 9.0.1.0 in Mac OS X Mountain Lion.

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I believe the Attributes are there from the beginning. (Try ??.) Therefore the question is: what happened to the usage message? Correct? When the system is in the second "mode" what do you get if you enter Sin::usage? –  Mr.Wizard Aug 15 at 16:39
Now I'm afraid if I terminate the kernel I won't able to regenerate the issue. But I think using "?" for built-in function won't generate Attributes. Now in the second "mode" after I enter ??Sin, the same output as ?Sin appears. After I enter Sin::usage?, nothing appears. –  Joe Li Aug 15 at 16:53
In a fresh session ??Sin produces the usage line as shown in your first example and the Attributes line shown in the second. For Sin::usage just enter it by itself on a new line. It should output "Sin[z] gives the sine of z." If it does not something is causing that to be lost; possibly a bug in one of the packages that is auto-loaded when you use a particular function. –  Mr.Wizard Aug 15 at 16:57
Does this happen with all notebooks, or just one or two? –  rcollyer Aug 15 at 17:23
I restart the kernel and tried all the input between the last "?" input that worked and the one that failed, and not able to regenerate the issue again. It should be note that the output SystemSin` suggesting the kernel treat the built-in function as a user defined function. –  Joe Li Aug 15 at 17:26
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