Webpage application stuck waiting on a javascript

I am testing an application. When I click on a hyperlink on a page, it opens up a popup window. The window displays loading as the text on it and that's about it. It does not complete loading.

I opened the Internet Explorer debugger(F12) and then navigated to the Network tab. I re-ran the test, this time I was recording the network activity. When I go through all the requests, I observed that there is one request, a request for a javascript that is stuck in pending. I copied the URL to the js and tried to request it via another browser instance, it works ok. I am able to fetch the js. I am not educated enough to debug this issue. Any help would be appreciated.

FYI, I am using Internet explorer and I am an application tester, having no access to the application code. I am seeing this issue on some of our servers and not on others.