Since the maintenance last night, some people are still having issues with connecting this morning.
This is due to the login server changed IP address in the process.
EDIT: First of all, if your pc was on during the whole thing, it is suggested to restart it, if that don't work, read on.
If your PC are not able to connect there are 3 potential workarounds. They are:Step 1.
Power of your router/modem, wait about 30 seconds, then power it back on, if problem persist continue to step 2.Step 2.
In "Run" (XP), or Search field in start menu (Win7), type "CMD" and run it (it is command prompt). in it type:
If problem persist continue to step 3.Step 3.
This is a temporary solution and you will need to remove this entry if you experience problems in future (when the ip change again).
Locate c:\windows\system32\drivers\etc\hosts and open it in notepad
On a blank line put the following
a # infront.
Save file as you found it, some versions of windows might want to play tricks on you and add .txt, is important it is saved without any extension.