The U.S. Department of State announced on June 12, 2015, that it was again experiencing technical problems with its computer systems, which are delaying the processing of non-immigrant visa applications.
These technical problems are not limited to a particular type of application, and therefore, Mexican citizens seeking TN visa stamps at the U.S. Embassy/Consulates may experience delays of unknown duration in the processing of their applications. Individuals should consider rescheduling their application filings until after the Department of State has fixed this problem.
The technical problems happening at the Department of State should not have any impact on the processing of TN applications filed at the border by Canadian citizens, or on I-129 petitions requesting TN status filed with USCIS on behalf of either Canadian or Mexican citizens.
UPDATE 6/22/2015: The U.S. Department of State has announced that they are still having technical issues with visa applications, but hope to have the system fixed sometime this week.
UPDATE 6/25/2015: As of yesterday, the U.S. Department of State has announced that 73% of the U.S. embassies/consulates are now issuing non-immigrant visas, and that the remaining offices will be ready to do so "in a few days." All posts are conducting interviews. The DOS has a list of all the posts that are issuing visas at the link above.
UPDATE 6/29/2015: The U.S. Department of State has announced that all of the U.S. embassies/consulates are now online and issuing non-immigrant visas, and that the majority of its backlog has been cleared.