I ran into an error a few days ago where when uploading a mp4 file to the website, which I've done many times before without troubles, it lingers on the uploading screen for anywhere from 5-20 minutes, and then at random, will pop up with the error posted below. I've never received this error before, but for the past few days I've been receiving this error every single time i try to upload a file. I haven't changed anything on my PC, no new pop-up blockers or firewalls. I am not a computer genius, so simple word explanations would be great. Thanks!

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An AJAX HTTP request terminated abnormally.
Debugging information follows.
Path: /?q=file/ajax/field_videos/und/form-c30D5Qa8L45twtR99WMuQSI0_3FLHlMRNluyLr-y02I
StatusText: n/a
ResponseText: Uncaught exception thrown in session handler.PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away in _drupal_session_write() (line 209 of /home/**my user name**/public_html/includes/session.inc).
ReadyState: undefined