Layout index damaged

Issue report by vege

Product

FileMaker Pro

Version

FM Pro Advanced 11

Operating system version

Windows Vista SP 2

Description of the issue

Hello,
I have a problem with an old, huge database containing about 270 layouts (in one of the tables). Yesterday I added several new tables and started to reorganize the layouts in the original table, deleting some, creating others and adding about 20 layout folders.
Since then the layouts are not indexed correctly anymore: If I try to move to a layout by using the drop-down menu (which is important for the users), I will be directed to the last layout whenever the consecutive number of the layout is 256 or higher (the life-time number of layouts being about 1.000 including the folders, which, as I have learned from the recovery file, are obviously counted twice). And if I change from that to the preceding layout by using a script or switching into layout mode, the check mark in the drop-down menu will stay with the last. Layout folders beyond consecutive number 256 are not shown at all.
This is very annoying, since I have to decide whether or not to rebuild the database completely which would be a lot of work.
So, I need advice.
Greetings, Vege