Java transformer.transform giving null pointer exception

Im trying to convert a xml (string) in a new xml using XSL. Im using the transformer.transform function. This already worked on the same machine, but doesnt work now.

Im getting a java null pointer exception.

I don´t get any more detail about this error. The xml input is the same as always and doesnt have any null value. The only additional thing I can get while deugging is that in an internal function the "Europe/London" value is given that null pointer exception. The transformer method doesnt return more error info, so I suppose the method doesnt work due to this error.

Im using STS 3.1.0 with websphere 7.0.

Any ideas on this?

thank you,

fwu