Same thing has been happening to me on and off for a few weeks now.
I use VWS and never had issues with it. Problems started with the VWSaprs not updating on the normal schedule of every 10 minutes, so I tried every 20 minutes, then 30 minutes. No matter what options, it would update automatically for a few hours, then stop sending data. I even went back to the older version and same thing, so just did a reset of my computer, and so far the newer version is still working (for how long, I do not know). Seems like at this point, that issue has been resolved.
My main problem though is similar to yours. I can no longer get forecasts like I have been able to get for many years.
I checked the mesonet map, and I noticed in the text information, that the last update was dated 02/18/12 for all
mesonet stations! There is definitely something wrong here. I am no longer able to get current updates, and nothing has been changed on my end.
I cannot even get into the wunderground website. Interestingly, I can get into the classic.wunderground.com website though, and my data is showing up there up to date.. Go Figure.
I must also add here, that I got into the ambient website, and strangely, I clicked on a link to enter the forum, and ended up being redirected to some other website. My Norton 360 immediately blocked that website, and notified me of a "Web Attack: Blackhole Toolkit Website 12" against my computer. The Attacking Computer's IP Address was 184.108.40.206,80. The Attacker URL was: 220.127.116.11/Home/index.php.
My computer is safe, and so is my website.
I don't seem to have a way to contact them to report this, but the Norton360, has sent this information to Symantic, so I'm sure they will handle it from there.
As for wunderground, I'm wondering if they too could be infected, or may have possibly been hit with a denial of service attack.