Yes the problems I had importing and exporting presets as well as missing previews in various extensions vanished when changing to english version OS (In my case I used Win XP SP3 32-bit swedish version up until now). With my limited knowledge I think the problems in my case has to do with the naming of the "users" folder in windows, swedish version.
"users" is named "användare" in swe version including a special character not available in most other languages except the Scandinavian. There also might be other files and folders named differently causing problems but I believe this must be the problem. Changing to english OS did the trick and all of my previous problems are now gone!