How to solve the 414 sites limit [4]

Sessions directory, the largest support only 414 sites, when more than 414 sites, the situation will become as follows.
How to solve this problem? Please master answers, and email me, thank you.
My email address is amormiosl@sohu.com

Program Ver. : Xshell 3.0

OH，I Forgot to say that， the OS running on my PC is Windows XP。

Keep an eye on the problem please,and solution as soon as possible.

Thank you