Acting on panic never helps investors, but it's still a good idea to play devil's advocate with investments.

Consider software developer Adobe Systems (Nasdaq: ADBE). Though it holds a significant share of the creative software tools market, you'll find a few of the 1,893 Motley Fool CAPS members weighing in on the company offer reasons to be bearish.

Here at the Motley Fool, we like to consider both the good and bad sides of an investment, so in this article, so I'm highlighting three of the main bearish arguments on Adobe today. Be sure to read the bullish side as well, and then weigh in with your own comments below or rate Adobe in CAPS.                                             

1. HTML5 is a credible threat
With the emerging HTML5 standard's ability to do much of what Flash does without third-party applications, some CAPS members see a major threat to Adobe's prized media platform. One RBC Capital analyst calls it an overhang that can't be ignored. With Apple (Nasdaq: AAPL) aggressively promoting HTML5, and Microsoft (Nasdaq: MSFT) supporting it in the upcoming Internet Explorer 9 browser, Flash may be up against some stiff competition.  

2. Security flaws
McAfee's (NYSE: MFE) "2010 Threat Predictions" report predicted that Adobe's Flash and Acrobat Reader software will become top targets for hackers this year. A similar report by Symantec (Nasdaq: SYMC) cited big growth in the number of PDF attacks taking place in 2009. Some CAPS members are concerned of the effects of security breaches on consumers' faith in products and Adobe's long-term growth. While Adobe has won support from Nokia (NYSE: NOK) and Google (Nasdaq: GOOG) in the smartphone market, security fears, among other concerns, have kept Flash off of the iPhone and iPad, potentially cutting out millions of users.  

3. Overpriced
Expectations have been high for Adobe, which now sits at a trailing multiple of nearly 47 times earnings. Its CAPS rating has fallen from five stars to three in fairly short order this year, as CAPS members increasingly think that Adobe's shares may be getting ahead of themselves. With cheaper alternatives out there, some investors are passing up a solid software company simply based upon price.                                  

To see details of what CAPS members are saying now about Adobe, just click on over to Motley Fool CAPS and have a look -- or add your own thoughts directly to this story in the comments box below.

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Fool contributor Dave Mock has found three more reasons to turn down those tempting telemarketer offers. He owns no shares of companies mentioned here. Microsoft and Nokia are Inside Value picks. Google is a Rule Breakers recommendation. Apple and Adobe are Stock Advisor picks. Motley Fool Options has recommended a diagonal call position on Microsoft. The Fool's disclosure policy used to wear a hairpiece but is finally comfortable enough with itself to go au natural.