Remember that when you are blocked from accessing one particular network and/or server that it is not anything to do with mIRC, it's down to the network administration. Some networks do not allow IRC access at all (except usually for their server staff) due to abuse. A java client is a way to access IRC via your web browser (e.g. Internet Explorer).
If you used to be able to get on to that network via an IRC client then you may wish to check out the network's website for information on why this has changed. Due to abuse some networks block access from AOL users (this is one of the unfortunate side effects of using AOL as they provide hostnames which change when a user reconnects, therefore, allowing ban evading - so some servers/networks/channels block all AOL access completely).
If SureChat wishes to block IRC access we cannot and will not help get around their blocks, you will need to use the Java applet they've provided, or indeed use another network.
Regards,
