Linux lite welcome screen stays black

[julien]

I installed Linux Lite 6.6 on an old iMac that is about 15 years old, just for fun and Linux Lite runs great on it. I used the entire hard drive. When booting I get the normal order: spinning wheel, mouse, and toolbar and then the welcome box that stays black;  I can remove the frame via the top right corner without any problems. Could the cause be that there is not enough RAM to load everything?  How can I prevent the frame from appearing?
ths.