Forum 4.0 to 4.0.1 upgrade and major problem.
 

I simply did the usual upgrade procedure, and afterwards I started having this awkward, but major problem.

Let's say I type in my username and password for the AdminCP, I click enter. All is well, then the loading page comes up that says "Thank you for logging in" and right below it is the usual button that states "Click here if your browser does not automatically redirect you. Well, right after this screen is where my problem is. For whatever reason, the browser redirects me to a URL with a back slash after the domain name. For example, it looks like this:

Code:
http://domain.com\/admincp/index.php
Obviously it does not load, and I get a server not found error. So I just simply remove the backslash and the AdminCP loads like usual.

NOW, this isn't the only time this mysterious backslash appears. I get the same backslash that appears after I click submit to post a new thread. I get an error, so then I manually remove the backslash for the URL and the thread is posted like normal?

And yes, I did disable all my plugins.