error can't find project or library

I have some vba Excel code that works when it is run on a windows 2000 OS PC But when I run the same code on an Windows XP OS PC I
get
Compile error can't find project or library

both PC have Office 2003 (Excel) installed

Debug brings me to

Private Sub UserForm_Initialize()
txtCurrentDate.Value = Format(Now(), "mm/dd/yyyy")
End Sub

If I get rid of the Format function it solves the error

Private Sub cmdEmail_Click()
If Trim(Me.txtEmployeeName) = "" Then
Me.txtEmployeeName.SetFocus
MsgBox "Employee Name is a Required Field", vbOKOnly, "Required Field"
Exit Sub
Else
Worksheets("LeaveRequested").[C5] = txtEmployeeName.Text
End If

If I get rid of the Trim function it solves the error



How can I resolve this issue so that my VBA code works on both Windows 2000 and XP OS???

Tools>refernces

it should have a checkbox and prefixing it should say 'MISSING'