php error on login page

I am having a php error on the login page. It doesnt seem to matter even if I go back to older versions of my phprunner project.
The error is:

Technical information

Error type 2

Error description Unknown: open(c:/wamp/tmp\sess_iv7b994gmhgbhnk69qf6vfaeb1, O_RDWR) failed: No such file or directory (2)

URL localhost/pm101124/login.php?

Error file Unknown

Error line 0

SQL query
More info