TEXT dissapearing when at the end of a line

has anyone else had a problem with text dissapearing. if i draw a text box and type, when i reach the end the text should continue on the next line but all the text dissapears completely. not sure at what point this started but it hasn't always done it. also, when pasting in large amounts of text the text box appears empty.

Check the leading in the Options Bar when you use the text tool. Set it to Auto.