Can't write sessions problem- session start

[mike_at_hull]

I am having a problem using sessions in my php. I think the problem is in my setup.

If I change the session.save_path in my php.ini to ="c:\tmp" it seems to write session variables ok - no error comes up. But when I try to retrieve the variables I get "undefined index" errors.

If I change the session.save_path to ="4:c:\tmp" or another integer number I get the following error when trying to write the session variables

"warning: session_start()[function session_start]: open (.....) failed: no such file or directory..."

When this happens the system tries to split up the session id into a number of subdirectories off the c:\tmp directory e.g. c:\tmp\f\d\0\s\b092.... this example would be if the node integer was set to 4.

I am running php 5 on apache 2 with MySQL 5 on windows XP ad I am accessing the server as a localhost. I have checked the permissions on the c:\tmp directory and they are ok and I have tried to use different directories to store sessions in, but it makes no difference.

Any ideas?