A sputtering economy, implosions at financial institutions, or just plain bad management -- on any given day, investors can name a number of reasons to sell a stock. Yet while panic is never beneficial to investors, it's good practice to play devil's advocate with investments from time to time.

In Motley Fool CAPS, more than 125,000 members have weighed in on nearly 5,400 stocks, sharing bullish and bearish opinions alike.

In the case of software stalwart Microsoft (NASDAQ:MSFT), a total of 12,460 members have weighed in on its chances of success. I've already plucked out some of the bullish rationale backing Microsoft today, so here are three counterpoints to consider, courtesy of CAPS:

Vista: Microsoft lost nearly half its value in 2008 as it faced a tough year like many other tech companies. But it wasn't all due to events outside the company -- many argue that Vista did a spectacular job at lowering the company, as the unpopular operating system was shunned by many corporate users.

Enemies advancing: Google (NASDAQ:GOOG) leads search advertising, and many think buying Yahoo! (NASDAQ:YHOO) is the only way Microsoft has a shot at competing. On top of this, Amazon.com (NASDAQ:AMZN) is a cloud computing threat, and Zune lags far behind Apple's (NASDAQ:AAPL) and SanDisk's (NASDAQ:SNDK) music players.

Oh yeah, and the once-ubiquitous Internet Explorer is losing ground to competitors.

Reached its peak: Providing more growth for shareholders becomes difficult for large companies like Microsoft or Oracle (NASDAQ:ORCL). To move the needle, Microsoft needs to make huge investments and take big risks. And lots of issues drag on the firm, such as antitrust suits that have already had the company shelling out over a billion dollars in fines to European regulators.

Of course, Microsoft has survived and thrived despite huge obstacles in the past. But the question about whether the company can do so going forward is why CAPS is such a great resource to augment your own analysis.

To see what the very best CAPS members are saying now about Microsoft, just click on over to Motley Fool CAPS and have a look -- it's all free, and open to your opinion.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.