A user has been granted access to a shared folder on a file server but is unable to open any of the files in the folder. The user is able to see the files and folders. Which of the following should the technician check first?

File extensions indicate the format of files and determine which applications can open them. While a mismatched file type could cause issues when trying to open a file, it does not affect the ability to see the files in the folder. Thus, checking file extensions is not a priority unless permissions are confirmed to be correct.

Network connectivity issues would typically prevent the user from seeing the shared folder or files altogether. Since the user can view the contents, it indicates that the network connection is functioning properly, making this option irrelevant for the current problem.

While antivirus settings can occasionally block access to files, this is less common than permission-related issues. Additionally, it would not explain why the user can see the files but not open them. Therefore, checking antivirus settings is a lower priority compared to confirming folder permissions.