Company Weakness or Systemic?

I have a few stocks in the tech sector I like to compare with each other.  I'm no fancy investor, but all of these companies have appealed to me at one time or another and it is interesting to watched their fortunes wax and wane.

At times like these you expect everything to go down a bit.  But what to make of a stock that has long led all the rest suddenly sinking to near the bottom?   At the same time, IBM and Microsoft, and old monopolist and a new have doggedly held their ground to come out on top.

Do these companies really deserve these valuations, or is it more about perception of non-technical stock analysts making sweeping generalizations (eg: high-end Apple products may no longer be in great demand)?