Chapter is invalid

Hi...
I am getting this error on a client's machine (XP)

When the program does a second filter on a recordset it gives him the above error.

Form1.DataGrid1.Columns("TCode").DataField = "TCode"
Form1.DataGrid1.Columns("TDescription").DataField = "TDesc"
Set Form1.DataGrid1.DataSource = DRS.DataSource

'User enters value to search on i.e. "S"
'Returns 3 records...Smith, Simonds, Sampson
rsDRS.Filter = "TCode LIKE '" & Form1.txtSearch.Text & "%'"
Set Form1.DataGrid1.DataSource = rsDRS.DataSource

This works fine, but if he types in another value to search on i.e. "Si" - "Chapter is invalid" error occurs.

Using MDAC2.7 SP1
All datatypes are strings

On another client's machine who is also running XP all if working perfectly....PLS HELP
:(