In tip 0064, we described one NoPopupsOnBoot registry entry.

You may also use Regedt32 to navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon

On the Edit menu, Add Value name NoPopupsOnBoot, this time as a type REG_SZ, and set the data value in the String Editor. The default is 0, which displays popups, while a 1 prevents popups.

NOTE: If you disable popups, be sure to checks the event logs.