Powerpoint code to close Excel file working incorrectly

Hello,

I am trying to automate a process that runs an access query, transfers the spreadsheet to an excel page, populates charts and graphs, and then uses these charts and graphs with other formatting to create PowerPoint slides.

Although my code seems to work well, when I log off the computer I am prompted to save changes for an "open" excel file, although it doesn't appear to be open. I think this is creating problems with my transferspreadhseet function in Access, because I am getting the error message "Too Many Fields Defined".

Here is a sample of my ppt code:

Set xlApp = CreateObject("Excel.Application")
Set xlWrkBook = xlApp.Workbooks.Open("\\Sfa19\bpmd$\Reporting\Patient Reporting - TSI\Patient Financial Reporting\Template Databases\Charts Master template.xls")

' Create a new slide
ActiveWindow.View.GotoSlide Index:=ActivePresentation.Slides.Add(Index:=1, Layout:=ppLayoutTitleOnly).SlideIndex

' Copy picture of the 1st chart object onto the clipboard
xlWrkBook.Worksheets("IP Variance Chart").ChartObjects("IP Variance Chart").Chart.CopyPicture

and so on.... until I reach the end of my code:

' Close the open workbook without saving changes
xlWrkBook.Close (False)
xlApp.Quit

Set xlApp = Nothing
Set xlWrkBook = Nothing

I a wondering if I am opening the Excel file too many times and am missing code that would work better??

Your help is so much appreciated!!
Thanks