There's been word of this virus thing flowing around (Thanks Ceras for pointing this out!). I did a forum search on the main wikia page and it looks like they are aware of it (It looks like it's a trojan that keeps resurfacing on the system). It seems others have gotten it from other wikias so it's not just not the Hetalia wikia giving it off. I haven't gotten it yet but I will keep you guys posted on any news regarding the issue.
Here's the link to the forum topic:
http://community.wikia.com/index.php?title=Forum:Virus_Detected,_Shut_down&t=20100206135157
Someone on the Hetalia LJ seems to have been battling the Vurdo trojan (Virtumonde). I'm not 100% percent certain if this that the Wikia is facing but gives off similar symptoms that this particlar trojan is giving off. Wikipedia has an article regarding it:
http://en.wikipedia.org/wiki/Vundo
If you're running on Mac or Linux, then this shouldn't affect you. From what it looks like, it's targeting PC users only. And the Vurdo trojan targets only PC users running on systems Windows 95, 98, 98SE, NT, ME, 2000, and XP. Vista and 7 are not affected by Vurdo.
It's current unknown how people are getting this trojan but if people are getting this through the ads, then I HIGHLY recommend going to FireFox (if you haven't already) and get the popular add-on Ad-Block Plus installed. Also, make sure your anti-virus system is updated. If you don't have one, AVG is usually a recommended choice by many.
Again, I'll keep you guys updated. As your admin and friend, I want to keep you guys safe and trojan-free. Plus, I have unhealthly obsession for researching on viruses and trojans so this stuff is right up my alley. I'm also a bit of a computer-nerd.
Update (08/02/2010)[]
I just got an update regarding the issue. Looks like it was malware issues thanks to our friends, the ads, which is why a bunch of people had their anti-virus programs freaking out. You can read more about this here:
http://community.wikia.com/wiki/User_blog:KyleH/Malware_warnings_on_Wikia