Could Not Save All The Data And Formatting Recently Added

I am running the below code to basically apply a defined list to a cell containing the string "WORKDAMNIT". This list is used as validation. I am running into a HUGE problem where once I apply the validation on about 17,000 cells and try to save the spreadsheet I get an error saying that "Excel could not save all the data and formatting you recently added to...". Thus, the IF loop basically does a save of records everytime I hit about 1000 records. I can even see the file being saved. However, whenever I close the spreadsheet it asks me to SAVE!! If I try to save it I get the same error and if I dont NOTHING gets saved.

Sub Valid()

Dim listCount As Long 'counter
Dim cellCount As Long 'cell Counter for save function
Dim foundCell As Range 'found cell in sheet Find
Dim foundList As Range 'found cell in sheet list
Dim fwb As Workbook 'workbook value
Dim fsheet1 As String 'find sheet
Dim fsheet2 As String 'list sheet
Dim strMatchCol As Integer 'address value of column number
Dim col As String 'actual value of column string
Dim strFind As String 'The string we are searching for (eg. "blah blah")

Set fwb = ActiveWorkbook
fsheet1 = "Data"