Need to delete cookies to continue use

Anyone else had the problem that you can use the site for so long and then all of sudden just get the dreaded white page? I've then found that if I clear the Cookies out it works fine for a while until...........
This has only started since the changeover.
(Firefox on Vista Business)
This has only started since the changeover.
(Firefox on Vista Business)
Trail fun - Transition Bandit
Road - Wilier Izoard Centaur/Cube Agree C62 Disc
Allround - Cotic Solaris
Road - Wilier Izoard Centaur/Cube Agree C62 Disc
Allround - Cotic Solaris
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Road - Wilier Izoard Centaur/Cube Agree C62 Disc
Allround - Cotic Solaris
Firefox btw.