AdiIRC

Maybe the registered nick is banned from the channel, check the status window for channel error messages.

No, it's not because I can still access it with my old laptop. The odd thing is, when I enter the room with a non-registered nick I can then switch to my registered nick and I'll stay in the room, but I can't change my nick at all after that and can't go into any other rooms just like if I had started out with a registered nick.

If you check here https://wiki.zandronum.com/IRC:Channel_Modes, there are some servers with channel modes that doesn't allow you to change nick while in the channel or only allow nick change a specific number of times during a time period, might be related.

The difference between your new/old laptop might be how you have setup your nickserv auth and autojoin/delay join, I suggest opening serverlist on both and compare what options you have set and see if there are any difference.

If you can't find any differences, you can try copying your AdiIRC config files over. Type //echo $adiircdir in the Editbox in AdiIRC on both old/new laptops to open the config folder.

It has nothing to do with the server or changing nicks too often or anything, I can promise you that. The same things I was doing with my old laptop is the same things I'm trying to do with my new one.

I also don't have any autojoin/delay settings, so nothing to do with that and both of my serverlists look the same.

Also, as you suggested I copied both the config.ini and config.bak files over to the new laptop and still the same problem. At least, I think that's what you meant... honestly I'm not sure what the editbox is... but there's a config files option in the Tools dropdown menu that takes me to a folder, so I'm guessing it's that.

The program works just fine when I have an unregistered nick, but seems to completely fail with my registered nick, whether I'm joining the server with it or changing it while in the server. People say they see me join the room, but I don't see the window at all, can't type in the room and can't receive PM's

The Editbox is where you type messages.

Did you compare your Serverlist settings, assuming you are using the Serverlist to connect to networks, and if so, did you also copy networks.ini?

Are you using a ZNC bouncer?

It sounds like AdiIRC thinks you have a different current nick than what the server is using, this would explain why joining a channel doesn't open the channel window since the nick joining the channel doesn't match your own and AdiIRC ignores it.

It's easy to verify this by disconnecting the server, then open Menubar -> File -> Rawlog, re-connect to the server and try to join a channel, after it fails, go back to the Rawlog window, in the Rawlog sidebar select the server, then click the "Save" button to save the log to a file, email that log file to me at amundsen@gmail.com and I'll have a look.

No, not using ZNC bouncer and both my serverlists look the same, except for some reason the username password part near the middle... The circled red area in the attached picture shows up on my old laptop but not on my new one, not sure why and can't figure out how to make it show up.

No, didn't copy networks.ini before. Just tried copying both network files, the commands file and both AdiIRCAP files. I closed the program and then logged back on and tried to get into a room after each one was copied over and nothing was fixed. Still having the same problem... the stuff in the red circle also didn't show up after copying any of the files.

Probably because the old laptop uses a newer version of AdiIRC while the new laptop uses 3.0 for some reason.

I keep all my old program download files, the ones I like anyway, so I don't have to go to every website and download them all again when I get a new computer, I can just auto-update. Never occurred to me that function might have a bug. But I updated, and all is good again. Thanks for being so patient and helping.