kmail index problem

Hi all, I have trinity (3.5.13) installed on debian wheezy. I just set up a new machine with the Haswell chipset and copied my installation on the new machine (I used clonezilla for that). As wheezy does not support Haswell, I had to install the 3.12-0.bpo.1 kernel. I also has a small problem setting the time (I mixed up dd/mm/yyyy and mm/dd/yyy). Now I get a message every time I start kmail, saying there was a problem with the indexes. kmail recreates the indexes and does work, but it does not cure the problem (I also deleted all indexes, *.index and *.ids, but it does not help either). the permissions seems ok (644) and the owner is right. Anyone has an idea what's going on? Thierry