Have you ever noticed something online that you couldn't explain and was more than a little creepy? You're not alone. Whether it's sites that seem to looking back at you or Facebook profiles that update themselves, the Internet has a ghost problem. Who ya gonna call?

That would be us. There are logical explanations for all the different kinds of weirdness you might encounter online, from creepy websites to demons taking over your PC. We've determined the 10 freakiest threats on the Net as well as the reality underlying — and explaining — each fright. Perhaps with a bit of understanding we can make friends with the ghosts in our PCs. Failing that, at least we'll know where to drive the stakes when the Internet Apocalypse begins. Guard yourself against our Internet hauntings, then share your own stories of Web weirdness in the comments below.

Phantom Websites
How It Haunts You: For all the currency and impermanence of Web content, phantom sites for defunct companies hang around long after the brick-and-mortar HQs go dark. At least Enron has finally replaced its long-lingering ghost site with a useful resource for its defunct stockholders.
What's Really Happening: Defunct corporate sites provide search links to wily usurpers, who buy up domain names to redirect traffic to their own pages. Internet ghosts also refer to those mistyped urls that generate hits on orbtiz.xom and Stuff.com.
Creep Factor: 2

Dead People on Facebook
How It Haunts You: MySpace and Facebook profiles of the recently departed stare back at you with creepy joie de vivre as depicted in tagged photos and interests in "music, dancing, and living life to the fullest" posted in, um, livelier times.
What's Really Happening: The major social-networking sites keep up the pages of its deceased members as places for friends to pay tribute; sites like MyDeathSpace.com link to said profiles for the sake of macabre voyeurism. Facebook, for one, extended its 30-day in memoriam policy following the Virginia Tech shootings. Scrabulous, RIP, was allowed no such honor.
Creep Factor: 8

Ads that Know You're Over 32 and Single
How It Haunts You: It's one thing that Facebook knows your relationship status. It's quite another when it turns that and all your other info over to salacious dating sites and pesky e-mail marketing services that post all-too-personal ads referring to your age, gender, and where you happen to be sitting.
What's Really Happening: Targeted ads — a.k.a. behavioral advertising — have evolved beyond Google keywords: unless you specify otherwise in your privacy settings, the information you provide in your profile is fair game for advertisers. Ditto your IP address, which is how your browser knows you're alone in that London hotel room.
Creep Factor: 6

Internet Ghosts
How It Haunts You: Speaking of Flash, Flash videos seem to be the most likely culprit for scaring the bejeezus out of us. Don't spook so easily? Check this out. Pay close attention: There's something not at all right about what you're seeing.
What's Really Happening: You're a non-believer, and your misconceptions about the non-existence of ghouls has been shaken. Why else would your friend have sent you to check that… or this or this out?
Creep Factor: 9

Demon PCs
How It Haunts You: As far back as 2000, religious leaders warned us of the evils of the PC, claiming that your hard drive had storage capacity enough to house demons—one Georgian preacher reported being openly mocked by a PC-dwelling spirit. Eight years later, the explosion of hate sites, terrorist how-tos, and posting boards for suicide seekers demonstrates that the devil isn't in the details— he's on the Web.
What's Really Happening: As the NRA espouses, guns don't kill people; ditto, the network isn't evil— people are. Luckily, even the notorious Suicide.Alt.Holiday Google group is proliferate with suicide prevention posts. As far as the preacher's promised opus on Satanic PCs: it was never written.
Creep Factor: 5

Personal Info Goes Public
How It Haunts You: Someone whispers to you at a pro-Obama dinner party that she knows about that unfortunate playground incident in Seattle. A anonymous stranger sends you a twisted gift that mocks your taste in music. And a neighbor asks about the money you donated to Bob Barr's wacky presidential campaign.
What's Really Happening: Formerly difficult-to-get (but still public) records are finding a much more accessible home online. If you're giving money to politicians, everyone's gonna know how to find you thanks to online public services like HuffPo's Fund Race and Family Watchdog. Creepy gifts could come from whack jobs checking out your Amazon wish list. On the flipside, though, now you can check out whether you share your political leanings with the cute dentist in apartment 12B.
Creep Factor: 4

Zombie Computers
How They Haunt You: Upon clicking into your browser's history, you discover that your PC was surfing during the night — by itself! Worse still, it spammed your entire contact list with emails whose subject lines read "DEEPER PENATRATION EASILY -- don't disapoint her tonite!!!"
What's Really Happening: It's not the undead that's infected your computer — it's malware. At some point, a seemingly innocuous .exe file was opened (likely by you) that turned your PC and Internet connection into a spamming bot to earn some hacker his money the "hard," fake-Viagra-selling way. You don't need a shovel and a shotgun to disable these zombies; you need Norton.
Creep Factor: 7

Hijacked Webcams
How They Haunt You: Ever get the feeling you're being watched? Or that, God forbid, the baby cam is tracking your child's every move? Forget hungry rats in the crib; pervy hackers on the Net is a far scarier concept.
What's Really Happening: Alas, the potential for remote access to your webcam is not so remote, after all: Adobe recently informed its Flash player users that visiting a malicious site could grant a "clickjacker" access to their webcam and microphone. Luckily, a fix is on the way. In the meantime, keep your pants on — literally.
Creep Factor: 8

Flying Toast, Exploding Coffee, Undercooked Burrito
How They Haunt You: Poltergeists just love to muck with your breakfast, jettisoning your Pop Tart from the Web-ready toaster and informing you your eggs are 40 years spoilt via the connected refrigerator. At this rate, you'll suffer a Micky D's high fructose-syrup-injected pancake roll-up to avoid trying to cook.
What's Really Happening: The smart home is a long ways off, still, from Jetsonian self-reliance, but appliance makers have already begun sticking Wi-Fi in their wares for the sake of "convenience." Microwaves that know how long to cook popcorn based on the UPC code, fridges that also warm food at your cell call prompt, and coffee makers that tell you how rainy and cold your day will be are all out there… and awaiting a teenage hacker's creative input.
Creep Factor: 8

Internet Sentience
How It Haunts You: The more interconnected our apps — hello, Gmail/Google Calendar/Google Docs/Google Missile Defense — the more inextricably our lives get tangled up in the Web's sticky net. How far off is SkyNet? It's already here, albeit as a poorly named British defense system lacking the Terminator's learning capabilities.
What's Really Happening: Sure, a total WWW melt-down would inconvenience us for a few years or so, but the reality is a system of safeguards protecting your bank account and nuclear codes from a power outage. If such a super-crisis ever occurs, the probable culprit will be human error. The chance of an intelligent entity emerging from the Internet is about as likely as the Wachowski brothers actually writing a good Matrix sequel. That said, there's still a chance…
Creep Factor: 3 (Potentially 10)