Worst banner ad ever - system doctor takes over the browser

ARrrggh! Have any of you met that super annoying ad that takes over your browser - even firefox on Mac - and hides all the windows while showing a very serious looking alert that reads:

https://www.systemdoctor.com
NOTICE: If your computer has errors in the registry database or file system, it could cause unpredictable or erratic behaviour, freezes and crashes. Fixing these errors can increase your computer's performance and prevent data loss. Would you like to install SystemDoctor to check your computer for free? (Recommended)
CANCEL / OK

No matter what you do, you'll still have to go to the systemdoctor webpage eventually, cancel doesn't actually cancel. Brave souls who want to see how the ad works might try copy-pasting this link into their browsers.
https://www.systemdoctor.com/download/2006/
?p=19&ax=1&ex=1&ed=2&mpt=[CACHEBUSTER]&aid=edgerest
(more inside)

The next panel/window appears after clicking either cancel or OK - and tries to freak you out even more, just in case that temporary "hide" of all your browser windows didn't get your attention:

https://www.systemdoctor.com
NOTICE: You have not completed the errors scan. If your computer has errors in file system or Windows registry, it could cause unpredictable or erratic PC behavior, freezes, crashes and loss of data.
You need to install SystemDoctor to scan for, and if found, fix system errors now (Recommended)?
CANCEL / OK

browsers will start an automatic download anyway - throw that crap away! And if you can, change your preferences/settings so that you have to approve each and every download from the web, it's safer that way.
System Doctor brags that it is 100% adware and spyware free, but is classified as adware. McAfee has gone all the way with this thing and shows what happens once it is installed - yeah, it'll ask you for your creditcard details. Yuck.
Meanwhile, if you have Firefox and adblock the advertising host of this ugly ad is adbrite, so in adblock you should block *.adbrite.com/* to ensure never having to go throough this sneaky javascript alert and redirect again. If you happen to be a webmaster who uses adbrite for your ads, consider checking that you never show this one since it'll prevent your visitors from seeing your site and that's probably not what you wanted when you signed up for some extra cash.
Update August 18 2007 Hacking web banner networks sends banner ads from hated to feared