VS 2012 File Used by Another Process (Timer)

Hey Everyone -

I have a little snag. I have this code on a timer . It runs fine the first time, but when the timer ticks the second time I get the error "The process cannot access the file 'C:\test\jesterlog.txt' because it is being used by another process." Is there a simple way to just close the file? This seems very simple but I'm not seeing a clear cut way to just dispose or close the file. Thanks!