Stupidity is contagious. It gets us all from time to time. Even respectable companies can catch it. As I do every week, let's take a look at five dumb financial events this week that may make your head spin.

1. Playing games 
(NYSE: SNE) can't catch a break.

Still reeling from last month's hacker attack that compromised personal user data on its PlayStation Network, this week the consumer-electronics giant had to shut down its PC-based gaming network over similar attacks.

There were 24.6 million accounts on Sony Online Entertainment -- Sony's hub for EverQuest and other Web-based multiplayer games. Thousands of credit card numbers were apparently compromised.

How far does Sony think it will have to go to convince gamers that it's safe to play in its playground? Whatever it's thinking, it will probably have to try even harder.

2. Bad hand played
It's not just allegations of shady business practices overseas that's keeping Las Vegas Sands (NYSE: LVS) in check. It's also the sluggish earnings the company is dealing out.

The casino operator posted a profit of $0.37 a share in its latest quarter, falling well short of the $0.44 that analysts were targeting. Sands China is booming in Macau, but weakness at its original Vegas gambling resorts is forcing investors to reconsider the old adage that the house always wins.

3. And the cord-cutting continues
There's a lot of goodness in Comcast's (Nasdaq: CMCSA) latest quarterly report. Revenue soared by 32%, padded by its deal for a majority stake in NBCUniversal. Earnings grew, surpassing Wall Street expectations. Its Internet and broadband telephony accounts continue to grow nicely.

However, I keep finding myself harping over Comcast's video customers. This is, after all, the country's largest cable provider. Dabbling in content and using its pipes to deliver online connectivity and Web-enabled telephone service are smart moves, but isn't this a company that will ultimately live and die by its "Comcastic" couch potatoes?

Well, Comcast isn't doing so hot on that front. It shed another 39,000 cable television subscribers during the first three months of 2011. It now serves 714,000 fewer homes than it did a year ago.

The cord-cutting trend is real, and all of the Xfinity streaming initiatives and programming changes aren't stopping the bleeding.

4. Guiding light
If you ever want to hose down a blowout quarter, follow it up with ho-hum guidance.

Web-chat specialist LivePerson (Nasdaq: LPSN) found that out the hard way on Tuesday. Its shares took a 14% hit after leaving its full-year outlook intact despite beating Wall Street's estimates.

Is that so bad? Well, yes. LivePerson posted an adjusted profit of $0.09 a share for the period, ahead of its earlier range of $0.06 to $0.08. However, by sticking to its 2011 adjusted earnings-per-share range of $0.33 to $0.36, it's telegraphing weakness during the final nine months of the year.

LivePerson has a lot of upside. Its platform is being used by some of the largest consumer-facing companies to deliver instant and cost-effective customer support online. Perhaps one day its guidance will reflect that trend.

5. Playing games again
Shares of (Nasdaq: SOHU) and Baidu (Nasdaq: BIDU) fell by 9% and 5%, respectively, on Tuesday, after a Pacific Crest analyst waxed bearish on (Nasdaq: YOKU).

Really? I can see the knock on Youku. China's leading video-sharing site isn't profitable, and it faces stiff competition. The future is uncertain. However, Sohu and Baidu have been profitable for years, sporting chunky margins and heady growth rates.

We can't paint all Chinese dot-com darlings with the same broad strokes. For Sohu to tumble by more than Youku's 6% slide is ridiculous.

Which of these five moves do you think is the dumbest? Share your thoughts in the comments box below. In the meantime, you can add Sony or any other stock you like to My Watchlist, which will gather all of the Fool's coverage of that stock for you.