After installation and even some use, the ROES Client may fail to launch. If you have run ROES on the system before, then it's possible a saved setting is the issue and cleaning up to start fresh is the best bet.
First, open an Explorer window (click Start and Computer) and choose C: drive, then Users (or Documents and Settings for XP) and go into your user account folder.
Find the .roescache folder and permanently delete it (this may take some time), then see if ROES launches. If it still fails, in the same user login folder look for the folder starting with a period that applies to your lab/their ROES.
In that folder will be a file of the same name as the folder ending in .properties. Delete this .properties file, which stores old/saved preferences, and then try the launch again.