tedster - 7:26 pm on Oct 27, 2011 (gmt 0)
I am aware of the Panda update but I don't think the changes occured in this period?
Your symptoms do sound a lot like some Panda reports we've seen. Panda updates have occurred at more than one period. We're trying to keep track of all the dates, and the list is here: Panda Iteeration Dates [webmasterworld.com]
At this point in time, there are 8 Panda dates that we are certain of:
Feb 24, 2011
April 11, 2011
May 10, 2011
June 16, 2011
July 23, 2011
August 12, 2011
September 27, 2011
October 13, 2011
The last two dates (and Oct 13 in particular) were followed by several smaller "aftershocks" on various specific dates - Matt Cutts calls that "Panda Flux".