help with IE6

I have 2 browsers on my p.c. my default browser is I.E6 and I use this one all the time. I also have Netscape 7. I have this one as a back up.
For the last week I keep getting the message This page cannot be displayed on IE, but I can view pages fine in Netscape (I'm using this now to type this). I have recently updated everything I need from microsoft and I have just done a repair on IE but still cannot view pages. I had trouble updating my AV because of this (I eventually managed to do it this morning).
I do not download things from the internet, I have not installed any new software/hardware, and I have not uninstalled anything.
I clean up my cookies and my Temp Internet Files regularly (thanks to this forum for that )
Anybody got any ideas?
Thanks in advance.

Julie

 

Thank You Derek!!!!
I don't know why it was ticked though.
I had a boot up problem 5 days ago and had to start up in safe mode. Maybe something happened then.
I went online fine this afternoon.
The mind boggles!!
Once again, thanks.