Perverse behaviour of LR 3.4.1 on photo import

Question

After updating to 3.4.1 import seems to behave differently. It is perverse, counter-intuitive and frustrating (and almost certainly a user error!). Could somebody volunteer to help reduce my blood pressure?
Since the first LR beta in 2006 I have arranged my images in following structure (sorry this is wordy and maybe dificult to follow):
<LR Catalog No. x>
     <Major Category> - folder name expressed as text
          <year>  - folder name expressedas  'yyyy'
               <date of import> - folder name expressed as 'yyyymmdd'
I use PhotoMechanic to ingest (import)  images, which writes them into the LR catalog structure above and also onto a second hard disk, 'unknown' to LR, as a backup. PhotoMechanic scripts automatically create the lowest level folder names.
Immediately after the ingest LR has no knowlege of the new photos. I then import them, 'in-place' as it were, using the functions of LR. The file structure shown above then appears in the Folders panel on the LHS of the LR display.This has worked fine since 2007.
For the last few weeks of following this process - after the update to LR 3.4.1 - the import step within LR results in the <year>. folder now appearing at the same level as  the <Major Category> folder. So now the Folders Pane shows:
<2011>
     <20110604>
<Major Category>
     <2004>
     <2005>
     <2011>
          But no folder <20110604>
However, the structure actually on the hard disk, as viewed by Windows explorer, is as I expect it to be. The LR Folders Pane is inconsistent with the physical directory structure.
This problem looks similar to that posted by user Harveyabc about 2 days ago, with the topic 'wind 7 after importing, pics not appearing under My Pictures in left panel'
but the solution suggested there has no effect on my system. I am using 64 bit LR under Win 7 Home Premium edition.
Could I have some suggestions please?
Thanks
Tony

Answer 1

I should add some additional information: the import within LR results in 2 copies of a folder being created on the disk, but only one of them showing in the Folders Pane. For example, images in the folder <20110601> are imported into a new folder <2011-06-01> which LR creates and is shown in LR in this folder name, while the original folder (<20110601>) remains on the disk, still containing the original of the images, as placed there by PhotoMechanic.
I do not understand this action, nor how LR is choosing the format of the name of the new folder  it is creating.