I'm using ZAISS 9.3.014.000. Vista 32 SP2 Ultimate in Spanish, updated regularly through Windows updates.
After clicking a link to a web that I trust 100% (website removed) two small IE8 windows have appeared, the smaller hidden by the larger. Both appear in the taskbar with the IE icon and the title "System scanner - Windows Internet Explorer" (Vista shows the title and a small picture of the window as normal).
The larger and visible one doesn't look like an IE window, rather it looks like a Windows message. Its title is "Mensaje de página web" (this is Spanish, it means "Web page message"), the canvas has a yellow "!" triangle, the text "Warning! Your computer is at risk of malware attacks. We recommend you to check your system inmediately. Press OK to start the process now..." (this text goes in English), and a button "Aceptar" (Spanish this time, it means "OK"). It also has a "x" button to close it, no minimize or maximize ones.
Dragging the described window apart you can see the smaller window. This one looks like a real IE8 one but very small, and it's not resizable or movable. In the title bar you can read "System scanner - Wi..." at the left of the buttons to minimize, maximize and close. It has the left side of the upper IE8 bars but it's too small to have canvas.
Is this an attack or a legitimate Windows prompt? Is it wise to close the larger window (the one with the "Aceptar" (OK) button) with the "x" button in the upper right corner and perform a virus scan with ZAISS?