File Upload Control is not working while clicking on Browse Button

Hi All,
I have a webpage which consists of a fileupload control. For some reason, we opted sticking to using ASP.NET File Upload control. In different versions of IE am seeing on clicking the browse button, it would open a a dialog window prompting me to chose a file from a specific folder (Desktop as default path) and sometimes it would not. Instead, it would work fine by using spacebar in any version of IE. At first I observed this issue with IE 8, but later I realised and observed the same happened in 9 as well. When I googled, I found out that both IE 8 and 9 does not support XMLHttpRequest2 and so on. Surprisingly few days later, I see I am now able to see dialog window open by clicking on the browse button itself. I continue my research and later found out that Enabling/Disabling native XMLHttp under the Internet Options did the job for me. I checked and unchecked the radio button it did not work, but after I restart my system/close all instances of IE 8 I was ...