We have partitioned our Cadence tools among the IC technology we wish to explore with it and the Cadence version number we wish to run. To avoid problems create a directory from which you will run one (and only one!) Cadence start-up command (listed below). For example if you want to explore TSMC's 90-nm CMOS technology using version 5.10.41 create a directory like TSMC90nm go into it and start-up the Cadence tools with cad-tsmc905. Whenever you want to start up that tool for that technology go back to that directory and start-up Cadence. If you want any other tool and/or any other technology create a new directory and apply the appropriate start-up command.