I've just installed squid (latest) on my RH 7.2 box. I use NCSA_AUTH
for proxy_auth. I created user with:

htpasswd -cd /etc/squid/.squidpasswd username

Then the user could be authenticated and access the Internet with
success. However, for some hours ago, the user couldn't be
authenticated with his created username and password, unless I issued
the above command again.

I have to do this everyday.

Please help me.

Any solution would be greatly appreciated.