My qestion for php mapping gurus...

I have tried to crystalise my problem down as far as I can, if anyone
is still interested. To demonstrate I have two pages up, one with a map
on:
http://www.massivemap.com/firstpage.php
http://www.massivemap.com/secondpage.php
the pages link back to each other, ie keep clicking on the link at the
top and you go back and forth. If you do it enough times (10 or so) in
internet explorer enentually you just get a blank page. This what
happens on my main pages, except mugh more, about half the time. I
think it is something to do with setting cookies so I have set lots of
them to check this. You can see the script in MSWord format
at:http://www.massivemap.com/script.doc