Skype Disables Your Web Server!
The other day, I finally got around to doing an upgrade to my version of Skype. A short while later, I noticed that my web server (which I’d just started to use to create a new ASP.NET website) wasn’t working anymore. Naturally, I didn’t intially associate the two incidents, but the error message I got when attempting to start the web server included a dialogue about encountering error "0x8ffe2740". This particular error appears when there’s a port conflict starting the web server.
Now the web server, by industry convention, resides on port 80. This is well-known by anyone who’s ever done serious web development, and was certainly known to the developers of the Skype software. After running a portscan utility (called TcpView.exe), there I found Skype hogging port 80 on my system! Something applications should, by cocnvention, not be doing.
Turns out, under the instant messenger’s "Connection" tab, under the "Options" menu, there’s a checkbox labelled "User port 80 and 443 as altertatives for incoming connections". This checkbox wasn’t explicily selected by me, so I can only assume it appears by default, or perhaps by virtue of some kind of firewall detection logic (my network is router-firewalled) which might assume connections on other ports might be blocked, thus preventing Skpye from working. Regardless, if you want a working webserver while using Skpye, you may, following installation, have to double-check your Skpye options to be sure this checkbox is unchecked.
The trade-off is that while your webserver will restart afterward, Skype might not work. My firewall does allow Skype to work on other ports, without issue but many corporate network environments might not be so accomodating. Ultimately if Skype doesn’t work after chekcing this box off, you’ll have to check with your network administrator for more information.
One final option if you absolutely need Skype on ports 80 or 443 (the latter is for secure, encrypted web traffic) is to change your web serer port. You can do that by accessing the "Properties" dialogue from the "Internet Information Services" node of the "Computer Services" management console (located under the "Administrative Tools" folder off your Start / Programs menu in Windows).
For additional info on this issue, visit the Microsoft Support website – article Q816944.