http://it.megocollector.com/detail.asp?iFaq=230&iType=25

The annoying Runonce linking to runonce.msn.com/runonce2.aspx either fails to start or you do not want it to start.
There is no reasonable explaination as to the purpose of this link. All settings may be changed within the installation of itself without linking to Microsoft.
I have found solutions for IE 7 Beta 2 and other versions which included registry keys that are not required for the Gold release and I discovered a key that is required, not mentioned anywhere else.
To bypass IE7 Runonce
Create this registry file
----RunOnceDone.reg---------
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]
"RunOnceComplete"=dword:00000001
"RunOnceHasShown"=dword:00000001