I am having an issue with trying to run the period ending for accounts payable.  I was having this issue back in April 2014, but our support people fixed it, but it only worked successfully for a few months.  Now the same message is re-occurring and will not permit me to move forward to run the period ends.

The message is "The file AP VENDOR is being used by another task and cannot be opened".

This does not make sense as I am the only person authorized to get into AP.  Has anyone ran into this issue in the past and if so,how were you able to correct this?  Thanks for any help with this...