Acer 'Input not Supported'

I have had this monitor since it was new last year. I plugged it in and it was fine. 2 weeks ago after downloading Windows Vista updates and Adobe reader updates I get a floating grey box that says "Input not supported' on my next start-up.

I tried another monitor on my tower and that is fine. I tried the Acer monitor on another tower and no floating grey box. Why does it now do this on my computer?

FYI, I did adjust the resolution setting s as Acer tech Support suggested but that did nothing. I mean why was it fine for a year?

I'd appreciate any help/tips. Thanks.

I did that a bunch of times and even more so when tech support told me to. I had been using this monitor for over a year with no issues until I downloaded Windows Updates. I figured out over the weekend that my video card is over 8 yeras old and that maybe the new updates can't be handled by this card. I installed a new video card and problem solved. If you ever have to deal with Acer tech support be prepared to deal with alot of ineptitude.