See:-
http://forum.digitalfotonetz.de/viewtopic.php?t=83708&postdays=0&postorder=asc&start=0
via This PF Post.
The human translated quoted statements are quoted as below. (Yes, it has been quoted for times! ;-))
"According to a statement from Pentax Product Management, Pentax K-5 had a production problem within a specific serial number range. The problem is due to residues of a volatile material that sits between sensor surface and filter glass and which did not vanish/dissolve/disperse (don´t know the right word here. sorry ) completely. This problem is visible as string of pearls.
Cameras with a production date up to calendar week 49 are affected. Then Pentax became aware of this problem and shortly stopped the sale for a comprehensive investigation. During this time there was a delivery bottleneck and a waiting period.
Pentax solved the problem and cameras shipped from calendar week 50 2010 are free from the string of pearls symptom.
Customers with affected cameras can contact Pentax for a direct exchange of their cameras. Waiting times can occur due to short-term high demand and shortage of replacement cameras."
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