It would seem to suggest you have installed
GLT CAA1 Config Fix & Localization - if you don't think you have, perhaps some other GLT addon has this hidden within it's config.
This must be the case surely.
Does CAA1 run regardless of the error message?
One other very common cause for pbo's not to be found is when runniing a mission or script containing an error. It can be a
completely un-related error, but stops the correct loading of the mission and addons.
This will be very difficult to spot, check your arma2.rpt file.
Added 6 hours 23 minutes later:
Oh and yeah,
CAA1 is complete and closed.
The final version can be downloaded right here from Armaholic.
The final version did fixed almost all compatibility problems so the GLT fix probably isn't necessary.