That error message means that somewhere on your SparkPage or Message Board post, there is a greater or lesser than symbol, which the site does not allow. You should be able to hold down the control and f key at the same time and enter those symbols to search for them on the page. It should then take you to them on the page so you can delete them. Once you do that, you can then save your changes to your SparkPage or post your message.
"We either make ourselves happy or miserable. The amount of work is the same." Carlos Castaneda
Live Kind. Laugh Often. Love Always.