Can't enter text in certain input fields on IE7

I have a site with a search box that works fine in all browsers except IE7. Other textfields from the same site appear to work. Here is an example page:

http://rosettabooks.com/search/node

In IE7, I can enter text in the search field in the 'content' area of the page (the advanced search) but I cannot enter text in the search field in the navigation bar under the header. I have no problems with firefox/chrome/safari/ie8.

Granted, I am doing some hacky styling css in the problem text field to alter the submit button, but even commenting those out in the css has not seemed to rectify my problem.

Additionally, I can't install the ie developer tools to inspect the css on the windows side and can only use firebug with firefox to try to troubleshoot this.

I've seen similar issues with IE7 that involved re-registering a certain dll, but those cases开发者_JAVA百科 appear to be for people who cannot enter text at all anywhere, and that is not my problem. It seems to have something to do with my css, probably css on a parent element, but I can't seem to locate the problem.

A solution I found is to add for #search-box the following position:relative;z-index:100.

Try giving the "primary-menu" div a width of 650px or so. The problem is that that element is positioned above the text input.

There are times when IE7 lets <div> elements (well, any block element like that) expand horizontally to fill out to the container width even when the element is positioned specially.