Dynamic Range error When Multiple Workbooks Open

[troygeri]

In the attached spreadheet, I have a dynamic range defined which populates a dropdown

https://dl.dropboxusercontent.com/u/63479593/Enterprise Release Project Dashboard.xlsm

Dynamic Range Is

=OFFSET(Projects!$C$1,1,0,COUNTIF(Projects!$C:$C,">""")-1,2)

This populates a drop down in the Dashboard TAB under label Project ID & Name. In the code linked to this dropdown I have the following

Sub ComboBox1_Change()
ComboBox1.ListFillRange = "DynamicList"
With ThisWorkbook.Worksheets("Projects")
ProjDesc.Value = Application.VLookup(ComboBox1.Value, .Range("C2:T1000"), 3, 0)
TextBox1.Value = Application.VLookup(ComboBox1.Value, .Range("C2:T1000"), 5, 0)
TextBox2.Value = Application.VLookup(ComboBox1.Value, .Range("C2:T1000"), 6, 0)
TextBox3.Value = Application.VLookup(ComboBox1.Value, .Range("C2:T1000"), 7, 0)
End With
End Sub

This all works fine when I have only this one workbook opened, but as soon as I have a second spreadsheet open I start getting runtime errors related to the dynamiclist range, e.g below

 

[troygeri]

bump

 

[troygeri]

Really need help with this one guys

 

[troygeri]

bump...