MaimiTech,
From what you're saying, if you log under one user, you get errors, but if you use a different user, you don't.
Seems to me like some sort of permission issue. Check the permissions on the pdf files that you're trying to import, and make sure the user that has the errors has all permissions on the pdf. If it doesn't help, you might want to talk with your IT manager, so that he/she can double-check the permissions assigned to the user with the error, and compare what's different with the other one that works, and make the appropriate changes.
Regards,
Raphaël Lalonde Lefebvre