Problem with zaz tool/ cars.wad

I have following problem everytime i try to update cars.wad;
Exceptionerror occured in GP4LIB 0.8.108

Host: GP4LIB 0.8.108
Caller: GP4LIB
Procedure: frmMain::OpenWad
Date: 7-5-2011
Time: 13:34:38
Bad file name or number
Line: 138
Source: Easywad4

Os Info:
Unknown OS Version 6.1


6.1 b 7601

Nederlands (Nederland) (Dutch)

-------------Place some info here of how and when it happened-------------

What's up?

Pont