When you access Web pages from Internet Explorer 5.x and Internet Explorer 6.x, the actual text of an HTTP 500 message that is sent to the browser may be masked by an Internet Explorer "friendly" error message
Turn off the friendly error message option in the browser as follows:
a. In Internet Explorer 5.x and 6.x, on the Tools menu, click Internet Options.
b. On the Advanced tab, under the Browsing section, click to clear the Show friendly HTTP error messages check box, and then click OK.
c. Close the browser.