confirmed with winXP and W7, both under VirtualBox 4,1,8

It happens to about 50% of the available languages, for example Russian and Chinese, while for example German, French, Italian are OK.

It does not depend on script. We have Belorussian and Kazakh, but not Russian. We have Korean and Japanese, but not Chinese. We have Catalan, but not Spanish.

It does not depend on the order of storage transforms in MSI database. While languages at the end of the list are usually available, and the first half is usually not available, there are exceptions, for example Kazakh, which works and which was in the first half of the list. 

Log files (msiexec /L*v) are not very informative. In case of Calalan, which worked, I see the following lines in the log:

MSI (c) (30:C4) [12:10:44:923]: Looking for storage transform: 1027
MSI (c) (30:C4) [12:10:44:923]: Validating transform '1027' with validation bits 0
MSI (c) (30:C4) [12:10:44:939]: Transform '1027' is valid.

These lines are missing in case of pt-BR. But when I start installation with the explicit command: msiexec /i LibO<...>.msi TRANSFORMS=:1046, then I see pt-BR localized interface and similar lines in the log:

MSI (c) (1C:E4) [12:24:26:501]: Looking for storage transform: 1046
MSI (c) (1C:E4) [12:24:26:501]: Validating transform '1046' with validation bits 0
MSI (c) (1C:E4) [12:24:26:501]: Transform '1046' is valid.

I'm afraid it is a bug in MSI engine, maybe there are too many transforms.

Created attachment 55771 [details]
Select language dialog in the Abiword installer

> I'm afraid it is a bug in MSI engine, maybe there are too many transforms.

What about pt-PT?

In any case, maybe the best (and more elegant) solution is to have a first installer screen (like the one in the attached image from Abiword) where the installation language is suggested based on locale but the user can select manually.

Does this help with the problem of "too many transforms"?

(In reply to comment #3)
> What about pt-PT?

Same as the rest of the failing languages.

> Does this help with the problem of "too many transforms"?

No. Abiword's installer is not MSI.

> > Does this help with the problem of "too many transforms"?
> 
> No. Abiword's installer is not MSI.

I'm aware of that. I meant if deliberately selecting a language first could prevent the switching that occurs for some odd reason (the installer does start in Portuguese).

The language switch happens during the "Preparing to install..." stage. Even before the "Computing space requirements" dialog

In MSI the Summary Information -> Language field was truncated at 254 characters. It is possible that it cannot be longer than 254 characters, or the tools cannot add a longer string. It still needs to be investigated. We have 107 languages now and almost each has a 4 chars long LCID, plus the separating comma, so in this scheme we can support only 51 languages.

I have no idea if this applies to LO, but seems to be a solution to a similar problem
http://www.geektieguy.com/2010/03/13/create-a-multi-lingual-multi-language-msi-using-wix-and-custom-build-scripts/

fixed in master (-> 3.6)
review pending for 3.5

On RC2, after a fress install, the dialogs are in pt-BR,

However, on a customized installation where I removed tons of useless dictionaries, the UI is in english and not in pt-BR.

This is a serious issue.