We downloaded and installed 6.5.5 on Linux last night without problems. Everything installed easily and appears to be working fine except the Category ordering.
We can add an remove Categories without problems and they display in the main index, but we can't get them to maintain their order as we set them.
We order them 1 - 5 and when we hit the submit button, it indicates a successful update but then when you look at the category order again in the control panel Category section, they are all numbered with 0's.
We have attempted to place the order numbers in there several times and always get a successful update but the update must be correct???
It is a little confusing, but what I realized is that I had to change one and then click update. Then I changed another and click update, etc. I think the one that is highlighted is the one it changes.