IB shuts down on weekends for a number of reasons - mostly related to maintenance. However, the demos should be running. In any event, since the markets close and are unavailable for trading on weekends, this shouldn't be much of an issue. Weeknights are another matter. Each evening, the servers do reset and clients are unable to log in for about 1 to 1 1/2 hours. This mostly overlaps with the time Globex shuts down. Eventually we'll have a 24 hour system (i.e. no need to reset things) but for the time being we need to run a bunch of procedures each day. The reset for those on the US and Euro servers occurs over midnight. The Asian Server resets around 3 or 4 AM Hong Kong Time (currently a 12 hour time difference to the US). If you are really dead set on trading around the clock, I suggest you open up a second account and send a mail to the help desk (attn: HK help desk) requesting that it be placed on the Asian server.
So you can't log in using the same account on different servers? Isn't it pretty simple to share logins on world-wide servers or do you keep all of servers/acconts totally separate?