1. Try renaming the P:\ppart\Merge Temp folder to P:\ppart\Merge Temp.MMDDYYY 
  2. Have the site retry to merge.  If it doesn't work try number 3 and 4 below
  3. From an Administrative command prompt, go to the ppart folder and type "copy ctempty\????00.* ????02.*" and enter "A" for all
  4. While still in the ppart directory type: "copy ??????00.* ??????02.* and enter "A" for all
  5. Rename the Merge Temp Folder again and have the site retry the merge