JNI (JNIC) warned last night, sending shivers down not only the spines of its shareholders, but owners of Sun Microsystems (SUNW) - Get Report shares as well, saying that weakness in Sun's server market caused it to revise its first-quarter forecasts.

You see, JNI makes adapters for computer storage networks. If you think of Sun's servers as tin cans, then JNI makes the knots that bind the string to those cans.

In morning trading, JNI shares were down 13.7% to $7.88 and Sun shares were off 5.5% to $14.98.

As a result of the warning, Wall Street analysts look another look at Sun's bottom and top lines. Some didn't like what they saw, like

Bear Stearns'

Andrew Neff. The analyst trimmed his 2001 earnings forecast on Sun for the fourth time since January, dropping it to 40 cents from 50 cents a share -- the current consensus estimate. "Given continued weakness in enterprise markets, particularly in the high end and (given) deteriorating economic conditions, primarily in the U.S. though clearly spreading to international markets -- we are again lowering estimates," he wrote.

Neff didn't exactly have great things to say about JNI, either. He also dropped 2001 estimates on the company, lowering it to 3 cents from 6 cents a share, in line with last night's revised guidance. Low visibility was one reason for the revision, but Neff said the company needs to rely on more than Sun's business to get ahead. "While JNI has built a good competitive position in the Sun Solaris platform, it will have to expand beyond this base and get design wins with other server original equipment manufacturers and on other operating systems," he wrote.

Lehman Brothers

analyst George Elling, who expects Sun to make 48 cents a share in fiscal 2001, took JNI's weakness as yet another sign that Sun will probably have to revise its numbers again, with the economic climate so poor and a price war on the horizon. He did not, however, lower his strong buy rating on the stock or reduce any of his profit estimates.

"Clearly, Sun is facing difficult comparisons, and in addition, visibility and momentum are lacking. Our Sun sales contacts have indicated the company is engaged in very aggressive pricing, which creates the possibility for further margin erosion beyond our recently pared estimates," he wrote. "In light of the recent lack of visibility, we believe further estimate cuts are possible."

Merrill Lynch's

Thomas Kraemer also said that Sun has a high risk of making a negative preannouncement before it releases third-quarter earnings after the closing bell on April 19.