Language issue: German spellchecking in Calc buggy

Like in the subject: I (edit: sometimes) cannot choose german language for spellchecking in LibreOfficeCalc Portable. I can choose Dänisch (danish), the list entry before Deutsch (german), but when selecting german, it always jumps to English (USA). I can select other entries, but german simply is unselectable. Autocorrection does not work (edit: then) either.
Thesaurus and syllable division work, though.
I reinstalled the full install (clean install) because I used the experimental remove unwanted languages feature at first, but no luck, same issue.
I use LibreOfficePortable Multi with all languages installed locally (standard X:\PortableApps\LibreOfficePortable) on WinXP SP3 admin.
-edit-
Further investigation results:
Only occurs after transferring textblocks from Writer to Calc (copy paste). Workaround: Choosing Standard format for pasted cells resolves the issue...