Short-suffering Dell (DELL) shareholder Carl Icahn is not going to take this lying down -- this being what he says is a weak, unacceptable bid for the Round Rock, Texas, computer maker.

Where did he come from, you might ask? It turns out he now owns a large stake in Dell, and he's telling founder Michael Dell and Silver Lake Partners, who are trying to lead a buyout of the company, that it won't be happening the way they expect if he has anything to say about it.

Icahn, a billionaire investor, is claiming to have become one of the top outside investors in Dell recently, with his stake reported on CNBC as being around 6%. Rather than seeing the company acquired for $13.65 a share, or some $24 billion, Icahn says Dell needs to be prepared to pay a $9-a-share special dividend should shareholders vote the purchase down. When added to his view of the company's value at $13.81, that would make the stock worth $22.81. If the buyout group and the board don't want to change direction, Icahn says they should get ready for potentially years of lawsuits.

There could be good news here for the retail investor, even if it's not about them, and it isn't. Dell's shares bounced late Wednesday when rumors began to circulate about Icahn.

Recently, they were down 6 cents from the prior close at $14.26, but they are trending upward from the acquisition price -- only recently did the stock make it above $14. However, it remains several points beneath its 52-week high. If you're an ordinary person with some Dell shares, and Icahn succeeds in getting you a few more dollars, you'll have reason to cheer. The bad news would be if the takeover were in fact pulled and the stock slid back to the single digits, where it was as recently as November.

Speculation of that particular sort aside, Dell -- the company and the founder, really -- does have a serious problem at this point. Icahn is rich, he isn't at all shy about attention from the press, and he'll be tenacious, gladly making his case as frequently as he can. See his fight with Bill Ackman over Herbalife (HLF) for evidence. Before Icahn got involved, holders of 14.7% of Dell's stock already had said they would vote against the plan or suggested that they might be leaning that way. The addition of Icahn would take that to more than 20%. Michael Dell himself had 15.7% of the shares as of Dec. 31.

Icahn is of course welcome to buy whatever he wants, but he's not someone who's been there through the glory and the gory for Dell and therefore expects to be compensated in accordance with his loyalty. A search of quarterly filings detailing his holdings back to 2003, including his most recent, shows that he has had no ownership position in Dell's stock previously. FactSet lists 1,068 institutional, fund or insider owners of Dell, and Icahn is absent from that list. So he's new here. His intentions are to make money for Carl Icahn and his investors, and that's fine. But if you're inclined to note such things, this isn't Southeastern Asset Management, a long-time holder and the biggest outside investor, which itself has been arguing that the offer is well under Dell's value.