Last year was a difficult one for Hewlett-Packard (NYSE:HPQ) shareholders, as the stock was down 46% during the year. Thus far in 2013, shares are up 37% while the Dow Jones Industrial Average (DJINDICES:^DJI) has risen 11%, but HP was up even more at one point. Shares are currently trading at $19.56, but on March 28, they closed at $23.84, the highest they've been in 2013.

So what happened?
During 2012, investors had very little confidence in the company, and the turnaround story was just beginning. But as the year came to an end, the company posted some decent results, and there were signs that the ship was heading in the right direction. The positive sentiment rolled into 2013, and new investors began piling into the stock and running the price higher.

That all ended when April started. Shares hit their 2013 high on the last trading day of March and have been on a downward slide ever since. The first week of April, HP lost 7.84% of its value, and one analyst may have hit HP's problem on the head. In an April 4 report, Bill Shope from Goldman Sachs predicted that shares would fall 31% from their closing price that Monday of $23.31. He argued that while the restructuring of the company would help, he thought any gains to be made were going to be wiped out by weaknesses in other areas of the company's business.  

Since Shope made his prediction, shares have fallen $3.75, or 16.08%. Shope's calls are looking pretty prescient right about now.

Two weeks ago, we saw an IDC report warning that personal computer shipments fell 13.9% in the first quarter -- the largest decline IDC has ever recorded -- while analysts were expecting a drop of just 7.7%. IDC cited weak demand for PCs and unfavorable results for Microsoft's (NASDAQ:MSFT) Windows 8. Back in the fall, when Windows 8 hit the market, many PC experts said the new operating system would pull the industry back from its recent slump, as consumers refreshed their software and hardware. That refresh cycle clearly hasn't taken hold yet.

Another unit of HP's business that may also begin showing weakness is the server side. The company has received some accolades for its newest Moonshot server line, with some saying the servers are ahead of their time while they take up 80% less space and use 89% less energy. CEO Meg Whitman calls the servers evolutionary and innovative, with the potential to begin a new revolution. I'm not so sure. I think this also may be an area in which the company will soon begin showing weakness. 

Consider that the mother of all server companies, IBM (NYSE:IBM) just announced quarterly earnings this past week and missed on the top and bottom lines. It was the company's first earnings miss since 2005. The main reason for the miss was weak demand in the IT hardware segment, and analysts think this is a bad sign moving forward for the whole industry, not just for IBM.

Lastly, the Blackstone Group decided this week to pull its bid to take HP's closest competitor, Dell (UNKNOWN:DELL.DL), private. While the reasons for the about-face haven't been revealed, and although the decision doesn't point to any one business unit in particular, it does say a little about the business as a whole.

HP needs to be hitting on all cylinders, and with PC sales slumping, that doesn't seem to be happening now. In fact, there's evidence suggesting it won't be happening later, either, as this industry continues to evolve.

Fool contributor Matt Thalman owns shares of Microsoft. The Motley Fool owns shares of IBM and Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.