Problems Installing ABAP Netweaver 7 - java.lang.NoClassDefFoundError:

When I try to install this version of a ABAP Netweaver in my notebook, with Windows XP, an error message appers saying that "java.lang.NoClassDefFoundError: runException in thread main "

I've already configured the enviroment variable and I've tested running javac through command line . The Microsoft Loopback adapter is configured too ( I think that this error dosent have any relation to this configuration).

The only topic that ive found in forum its here: Software Downloads and the solution propoused there doesn't works for me.

Can anyone help me?

Thanks