Big problem with svn:mergeinfo, feature branches and merging (reintegrate)

Hi,

I have big problems with reintegrating feature branches. I have this
problem only with one reposity location.

I show it on example:
1) I create branch ( feature branch )
2) I switch to this branch
3) I change/edit one file in this feature branch and commit ( the
filename which i change is
*_assets\CrystalShop\Crystal\Shop\Abstract.php_* )
3) I switch back to trunk and try reintegrate this feature branch back
to trunk
4) the result looks like this ( I show it with the help of the
TortoiseSVN ):
I decided, that I create video where is everything showed, so here are
links to the captured screens, one file is encoded by the xvid codec and
second in TechSmith Screen Capture Codec - tscc.dll:
http://www.megaupload.com/?d=2DQ0J9IQ
http://www.megaupload.com/?d=LMYSA74F

I must solve this problem somehow and I want to know 2 thinks:
- not what cause this problem, because I know that svn:mergeinfo
properties on subdirs and on files in subdirs cause this, BUT WHY IT'S SO
- and how can I resolve this problem ( I don't want to delete
svn:mergeinfo, but as I can see it's only one possible solution :(, or
i'm wrong?? )

Thanks for any advices and suggestions, because issue priority it's very
critical/blocker for me.