[ShadowAce]

...variable rainbow graphic in the upper left corner of the windows startup screen.

You don't have a magnet up there, do you?

[rstrahan]

I agree, sounds like an electro-magnetic source near the monitor. Normally a malware tries to take over the computer and you can’t run other programs.

So, look for that first. If you are concerned about malware, get Malwarebytes. Best on the market.

[Fresh Wind]

Magnets only affect CRT’s.

[editor-surveyor]

No magnet, and the graphic disappears after the startup screen.

The problem also disappears in MS DOS mode. (Autocad)