I have changed it as follows:
Const ForReading = 1
Const ForWriting = 2
Dim fso, MyFile
Set fso = CreateObject("Scripting.FileSystemObject")
Set objRegEx = CreateObject("VBScript.RegExp")
objRegEx.Pattern = "Files Infected"
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.OpenTextFile("C:\Temp\test.txt", ForReading)
Set TestFile = fso.CreateTextFile("c:\temp\virusfile.txt", True)
Set objFile = objFSO.OpenTextFile("C:\Temp\virusfile.txt", ForWriting)
Do Until objFile.AtEndOfStream
strSearchString = objFile.ReadLine
Set colMatches = objRegEx.Execute(strSearchString)
If colMatches.Count > 0 Then
For Each strMatch in colMatches
TestFile.WriteLine("Virus Found.")
TestFile.Close ()
Next
End If
Loop
objFile.Close
but I now get an error
Line: 12
Char: 1
Error: Permission denied
Code: 800A0046
Source: Microsoft VBScript runtime error