[Typo3] Cookies

[Michael Baker]

I've created a website for a client, but the client can't access the 
typo3 back end.

The client has a machine running Windows XP and runs Norton AntiVirus.

When the client tries to login to the typo3 back end, sometimes they 
can't login and the 'you need to have cookies enabled' screen comes up, 
and sometimes they can, but after a short but variable length of time 
each of the frames in the backend shows the 'you need to have cookies 
enabled' screen comes up.  This happens with both Windows Explorer and 
Firefox.  In Windows explorer I have set an explicit exception to allow 
cookies from my website and Firefox is accepting cookies from all sites.

My suspicion is that some third party software intercepting or deleting 
the cookies or cookie requests.  I don't know how to find it.

Any suggestions?

Michael.