The shares of First Solar, Inc. (NASDAQ: FSLR) have started the week on a rocky note. Not only did Friedman, Billings, Ramsey & Co. downgrade the stock from Market Perform to Underperform, the alternative energy issue was also the topic of a skeptical Barron's article over the weekend.

In a note to clients, brokerage firm Friedman cited weak polysilicon prices and the stock's overrich valuation for its downgrade. FSLR closed last Friday at $191.72 per share, compared to Friedman's price target of $110.

Meanwhile, the cautious Barron's write up [subscription required] observes that the Intersolar trade show begins Wednesday in Munich, and pits FSLR against many lower-priced rivals. "One leading customer says it will ditch First Solar's 'thin-film' panels if crystalline silicon alternatives keep getting cheaper.

That seems likely. Silicon prices are expected to drop another 30% by year end. First Solar profits -- and its shares -- could get cut in half," commented the financial paper.

Most investors consider Dell Computer (NASDAQ: DELL) a dog of a company. Since the firm's founder, Michael Dell, took over as CEO, his only real skill seems to be cutting costs. The firm has lost market share in the PC category and is behind companies like Hewlett-Packard Company (NYSE: HPQ) and International Business Machines Corp. (NYSE: IBM) in the server business.

CNBC's Jim Cramer has an audience of 600,000 for his Mad Money. But Barron's has gone to great lengths to investigate how his stock picks have performed and it has concluded that they lag the market averages by about five percentage points. Specifically, Barron's concluded that from May to December of 2008, the S&P 500 lost about 30% and "heeding Cramer's Buys and Sells would have added another five percentage points to that loss."

Cramer's Sells do better than his Buys. Specifically, his Sells outperformed the market on the downside by five percentage points while his Buys lost up to 10 percentage points more than the market. One finance professor estimated using options-market activity that betting against Cramer's Buy recommendations can yield 25% in a month.

ExxonMobil Corp. (NYSE: XOM) is scheduled to discuss fourth-quarter and year-end 2008 results tomorrow, January 30, in a conference call at 11:00 AM ET hosted by David Rosenthal, vice president -- investor relations. You can catch the live audio webcast of the call on the company's website.

For the quarter that saw a settlement with the EPA and DOJ, analysts polled by Thomson Reuters expect Exxon to report a profit of $1.45 per share, compared to $2.13 per share in the same period of the previous year. Revenue for the quarter is expected to total $69.1 billion, down 40.7% from a year ago. Exxon's earnings fell short of estimates in three of the past five quarters, by as much as 9.7%.

Were you wondering which sector of the U.S. economy would be next to take a dive from the year-old credit crunch? Well look no further, because Barron's [subscription required] reports that private equity firms like Apollo Global Management, Kohlberg Kravis Roberts, and Blackstone Group (NYSE: BX) are hurting gators thanks to too much borrowed money and the weak financial performance of the companies they bought. And business is way down, Barron's reports that through mid-August, the 2008 total deal volume "stood at $67 billion, versus more than $400 billion in the corresponding 2007 period."

This does not come as a surprise to me. In February 2007, I appeared on CNBC arguing that private equity had peaked. And I began to question its long-term viability back in August 2006 when Barron's Alan Abelson quoted my thoughts on the matter. The basic problem is that when debt is cheap, private equity booms and when it starts selling itself to the public, investors should hold onto their wallets for dear life. People who own private equity firms tap their superior knowledge of the coming downturn to convince the public to bail them out by buying their stock.

Barron's cites -- as evidence of trouble in private equity land -- examples of the declining value of the publicly traded debt in companies that private equity took private at too-high prices with too much borrowed money. It writes that bonds of "many companies taken private in the past two years have plunged to 50 cents on the dollar or less, signaling that investors fear they won't be fully repaid. Many companies that were the subjects of buyouts a year or two ago are so grossly over-leveraged that they're struggling simply to pay interest. If they were to default, debt investors would be stung, but equity investors would be even worse off; the value of their holdings would be deeply impaired or wiped out."