Investors slammed semiconductor stocks Thursday amid fears that demand for computer chips is drying up as the economic malaise plaguing the U.S. is spreading to the rest of the world.

Novellus Systems said Tuesday its first-quarter earnings would be lower than expected and its revenue would be at the low end of its forecast range, sending its shares down 5 percent.

It was a week of dramatic, even historic developments, sending the market hundreds of points in both directions, posing difficult calls  for any trader, much less an average investor.

It's a familiar refrain from strategists and fund managers, especially these days:  Think long-term.  Jensen Investment Management chairman Robert Millen and David Katz, chief investment officer of Matrix Asset Advisors, think that's the only way to go.