If you're attempting to launch the most recent versions of Skype on Windows XP, you might see an error reading "Failed to get proc address for GetLogicalProcessorInformation (KERNEL32.dll)". If you're seeing this error, it's because your installation of Windows XP isn't running the most recent Service Pack (SP3) from Microsoft.
To fix this error, you'll need to get SP3 for Windows XP.
The easiest way to get SP3 is to turn on Automatic Updates in Windows.
You can also install SP3 by using Windows Update at the Windows website.
After you've updated Windows XP to SP3, Skype will launch normally.
Note: If you're running the 64-bit version of Windows XP, there is no SP3; SP2 is the latest service pack for the 64-bit version of Windows XP. The procedure for updating to SP2 is the same as outlined above.