MySQL server for Windows help needed!

[iisuser]

Hello all!
I have Windows-2000 Server with IIS-5.0, PHP (4.3.0) and MySQL (3.23.55).
There are about 4000 users with their MySQL databases. Users can access databases using their PHP scripts. Only local users are allowed.
To create a user I use this command:
GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER ON `User_database` . * TO 'User'@'localhost' IDENTIFIED BY 'Pass';

The problem: after 3-4 hours of work, all users getting the error message: "Can't connect to MySQL database at localhost (10061)".
I can't connect to MySQL using mysql.exe with admin username and password too!
But MySQL service is still running! Restarting of MySQL service gives no result. Restarting of IIS gives no result.
Only reboot of server solves the problem.
But after 3-4 hours problem appears again!
Now I have to reboot server every 4 hours... It's crazy!
I have tryed everything I know. I going to crush my head into the wall

Here is my.ini file:
[mysqld]
basedir=C:/mysql
tmpdir=C:/mysql/tmp
datadir=E:/mysql/data
port=3306
skip-locking
default-character-set=latin1
set-variable = key_buffer=16M
set-variable = max_allowed_packet=1M
set-variable = thread_stack=128K
set-variable = flush_time=600
skip-innodb
set-variable = max_connections = 3000

And here is [MySQL] section of php.ini file:
[MySQL]
mysql.allow_persistent = Off
mysql.max_persistent = 200
mysql.max_links = 500
mysql.default_port = 3306
mysql.default_socket =
mysql.default_host =
mysql.default_user =
mysql.default_password =
mysql.connect_timeout = 60
mysql.trace_mode = Off

Please help! Thank you!
kostya_r@hotmail.com