I have received a few inquiries this fall so here is the scoop. It seems all thus far are using MS EI.
Here is what Admin says as he is the tech genius here.
The dual-login shouldn't be an issue. Logging into a forum is a very simple process. When you log in, it stores a small cookie to remember you from your last experience. If there's a login issue, it could be because the cookies or temp internet files are full (Go up to Tools and clear cookies and temp internet files), or your browser could be somewhat corrupted. Any user using Internet Explorer will EVENTUALLY get some sort of corruption. That browser has so many security holes and there's so many websites that exploit them, it's not if anymore it's when.