Firefox: Failure"nsresult: "0x80004005 (NS_ERROR_FAILURE)

Firefox: Failure"nsresult: "0x80004005 (NS_ERROR_FAILURE)

I faced with following error in Firefox 23(this code works fine in IE and
Chrome) during send of XMLHttpRequest:
[Exception... "Failure" nsresult: "0x80004005 (NS_ERROR_FAILURE)"
location: "JS frame :: :: loadUiDesXml :: line 1" data: no] {
message="Failure", result=2147500037, name="NS_ERROR_FAILURE", more...}
I can't google what 2147500037 error means and this error is very strange
for me. This is a piece of code:
var xmlHttp = new XMLHttpRequest();
if (typeof theFile === "string")
{
xmlHttp.open("POST",theFile,false);
}else{
xmlHttp.open("POST",theFile.baseURI,false);
}
xmlHttp.send("");
The file variable is "/emWeb_6-0/des/en/ld117/ept.xml", domen origin
policy shouldn't prevent this request. The most strange thing, that I can
recieve ept.xml in other pages. For example, I can recieve this file
successfully in the following scenario: 1. Recieve ept.xml file on page1.
2. Redirect to page2, recieve ept.xml again 3. Redirect to page3, recieve
some other files, including ept.xml 4. Redirect back to page1, recieve
status.xml, then I try to recieve ept.xml and I get error duting send("")
The network trace is the following:
POST ept.xml
POST ept.xml
POST pch.xml
POST node.xml
POST ftpRslt.xml
POST ept.xml
POST status.xml
POST status.xml
I can't execute xmlHttp.send("") here.
This code works inside frame, I think that it can be related with the
error. Can anyone explain what is the root cause of this?