No template found

[mohsart]

I have "No template found" on top of the front page.

Background:
I had a language issue that I fixed today.
The reason for the issue was that the wrong ISO code for Swedish had been used (se instead of sv).
So I exported the translations, changed the ISO code, copied all se.php files that gave errors to sv.php, imported the translations and finally went through all modules and mail folders and copied everything se to sv.
I kept the se files/folders in case there were other dependencies (eg a module only using the ISO information at install).

I tried swithing to the original theme but still have "No template found".

I cannot swear that this started after I started messing with the translations/languages, but I think it did.
Strange though that I have it regardless of language chosen (Swedish or English).

Any hints on where to start looking?

/Mats