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NEW YORK ( TheStreet) -- "The bears may be in hibernation, but they'll be back in a few days," Jim Cramer warned his "Mad Money" TV show viewers on Monday. He said when the short sellers return to this market, there will be trouble.

Cramer reiterated that he's not a believer in the "panic" theory, but he's also not a believer that "all is well" now that the markets have enjoyed a few up days. He said there are still simply too many unknowns in this market, and none of those unknowns has been solved.

In Europe, Cramer said it's clear that the ban on short selling is working, along with the Europeans stepping in to buy some of the ill-fated bonds that are causing many of the problems. But Cramer expects that the hedge funds and short sellers who make a living punishing bank stocks into oblivion will side-step the new rules in another few days, returning the markets to their volatile state.

Here at home, Cramer said that the U.S. is still dealing with all of the uncertainty surrounding its next round of debt talks, made all the murkier by the beginnings of next year's election cycle.

On the upside, there was the Motorola Mobility ( MMI) deal with Google ( GOOG), a reminder of just how cheap U.S. stocks have gotten, said Cramer. Many stocks are still undervalued, he said, but the markets won't acknowledge that value with the uncertainty looming.

Cramer once again advised investors to take profits where they can and raise cash. He said the the short sellers will be back in another two days and when they get here, there will likely be trouble.

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