Content not displaying, disappearing, loss if saved.

After the 6.x-1.10 update I'm experiencing the following problems (I'm running three sites):

1. First site - appears to work correctly, but on re-editing some style information is lost. Such as the color style within a span. Child Garland theme. Sample iteration:
   
   Select text
   Use text color tool
   Save
   Verify on separate browser (text edits done with Firefox, verified on Opera). Ok.
   Re-edit
   Previous text color tool use not displayed.
   
   The difference is that it goes from '<span style="color:#ff0000;">' to '<span><span>' on the second edit.
   
   
2. Second site - Editing current text content, that is visible on the front page, shows nothing. Literally, the entry box of the editor appears blank. However, you can see the html code initially, but it disappears on interpretation. Preview and save both show empty text. Currently I can't update the site. Child Zen theme.
   
   
3. Third site - appears to work correctly, though I've not extensively checked it. Child Zen theme.
   

What I believe it isn't:

1. Server related - I'm getting reproduction on both the online server and testing servers, with different versions of Apache and MySQL.
2. Permission related - I'm editing as Administrator on all sites.

Status Report -
Drupal Version: 6.25
CKEditor Version: 3.5
Database/Drupal Core Updates: Up to Date
PHP: 5.2.17 / 5.3.10 (testing server)
MySQL: 5.0.92 / 5.5.21 (testing server)
Important note: These sites are hosted on Linux. The first site above has the actual folder structure. The other two sites have soft links (ln -s) to /sites/all/modules. This allows the code to be easily updated but may have interaction. I bring this up because though it was working correctly under 6.x-1.9, changes in the code may have resulted in something that prevents soft linking. Currently Panels exhibits this behavior, though all other modules (28 total) do not.