TTU 15: TWA is not a valid Win32 application

Hi,
I have just installed TTU 15.00 from downloads to connect to a Teradata database 14.0. My computer is Windows XP SP3.
When I have tried to execute TWA (Teradata Workload Analyzer). I have got the error message: twa.exe is not a valid Win32 application.
Please, can anybody help me or tell me where I can download a valid TWA from the web page?. I don´t know if you can also download the previous TTUs (14.00, 13.10, 13.00) from the web page.
Thank you very much.
Regards,
Ricardo