How should I disconnect from an internet connection?

[Robert]

Recently when I disconnect from an internet connection (by clicking the X in the upper right corner) the computer otherwise works ok but it will not reconnect to internet. It says "not responding." If I restart the computer it works ok.
Thank you, I have Internet Explorer on Windows 7. As soon as I closed my question I remembered (File and Exit) and found it works OK. So far I've had no troubles with any other application. If it turns out this is the beginning of more troubles, I'll have your suggestions to work from. Thanks again.