I found it ! \o/ The problem was that in my AJAXCheckUsername.jsp, I was not setting the content-type ! So I added this line : Response.addHeader("Content-Type: text/plain; charset=iso-8859-1");
Now Internet Explorer is not giving any error and it looks like Firefox is getting the response faster too (~150ms instead of ~300ms). Things to remember when using Ajax with IE ------------------------------------------ 1) Specify the content-type in the response object 2) Specify the cache directives (Pragma: no-cache, Cache-Control: no- cache, Expires: [past time]) Thanks for all your help on this ! I really appreciated your efforts ! 0xCAFE