Have to turn off IE “Protected Mode” to view web page, why?

Out application allows user to launch browser and show some web pages. The pages are in our company’s web site. This works fine on Windows XP. However, does not work on Vista. I can see a blank browser window only. To make it work, I have to turn off “Protected Mode” for both Internet and Local intranet from IE internet options, security tab.

As I understand, Protected Mode in Vista will prevent reading and writing to various areas of the file system and registry for low integrity processes like a browser. But I do not think our web page write any thing to client computer. Is there any tools can help us find out which part of the client computer that the web page try to access?

I an using Vista RC1 build 5600.

[1327 byte] By [jigsaw-ols] at [2008-2-15]