I just installed Ubunto 13.04 on a Mac Pro laptop under Parallel. It worked well and then because of the very small fonts I used a different screen setting. It worked well. Then I updated to 13.10. After the installation and restart the side bar is visible but the "working plane" is black. It seems some windows are being open, but cannot be seen. The menus with letters are seen but nothing more.
Can someone help, please?