That looks like an error from the webserver that hosts nzbmatrix.com, more than an error from Firefox. FF wouldn't tell you to run a mysqladmin command to correct anything.

The administrator in charge of nzbmatrix.com (or the webhoster) needs to take care of this problem, as it is not a Firefox issue.

I just visited nzbmatrix.com and the site seemed to work OK now, so perhaps try again.

I have receive following error dbconn: mysql_connect: Host 'nzbmatrix.com' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'

See solution above your entry. The problem is at nzbmatrix. The problem occurs every morning (well, it is morning for me) and they fix it every day, so if you get that error message, try again every hour until they have fixed it.