Please verify that your graphics card driver is the latest one available.
Is there any hint in the log file? Log file details can be set via the RobotExpert Doctor Tools menu.
I have come across something similar already. Problem was caused by the bad installation. The question is: Has RE worked before?
If not and the problems are from beginning, try to uninstall RE completely (maybe you will have to clean registry and some shared folders too) and then reinstall RE again. Before the second installation I suggest to switch off the User Account Control.
I recently ran into this at a customer site, turned out to be the processor was an i3. From the HW requirements:
CPU Minimum - Quad Core Duo
Optimal - Quad Core Duo