John, go to your user control panel which you can find by clicking on your name on any thread. Open my settings and on the left hand side you will get a list of options under your control panel. Down towards the bottom of that list is under settings and options is an "edit options" line. Click that and it will open the page you need to turn invisibility off. Untick it.
Did you know, that what you thought I said, was not what I meant :S