Display running in low-graphics mode

During startup I get a message box saying "Ubuntu is running in low-graphics mode", followed by a selection dialogue where I may select between
"Run Ubuntu in low-graphics mode for just one session"
"Reconfigure graphics"
"Troubleshoot the error"

I have tried all these and nothing has changed. Please help, please use simple english since I do not know the technical language. I was trying to see if I could figure it out from other people's postings but I could not.
Thanks in advance for your help.