Cursor disappears when writing text?

I have a frustrating problem in CS3 that when writing a block of text, either with text tool or area text tool, that the cursor disappears. I need to see its new position after using the space bar or tab: ready to input the next piece of text.
It seems to be flashing some of the time if I click into the middle of the text block, but disappears where I want to continue it at the bottom of the text block?