Question

It’s my first jQuery script, very short: http://jsfiddle.net/XGrJR/

in IE 7, when I click on a tab, the content just disappeared!

Answer 1

The id attribute must be unique. when you violate this rule you can never forecast what will happen.

From JQuery docs:

Each id value must be used only once within a document. If more than one element has been assigned the same ID, queries that use that ID will only select the first matched element in the DOM. This behavior should not be relied on, however; a document with more than one element using the same ID is invalid.

So your Javascript-jquery can be valid, but won’t work with invalid HTML.

I updated your’s JSFiddle with unique ids.