bonfire01

Have you already tried deleting your appdata\roaming\.techniclauncher folder and then restarting the launcher? Also I assume by single player you mean using technic is also resulting in you crashing on loading a map?

By "latest" tekkit do you mean 3.0? If you are then the minecraft screen will say it is running on MC version 1.2.5.. If you are all using that then the reason you can't connect is you are trying to connect a 1.2.5 client to a 1.1 server. There are no 1.2.5 server files at the moment so you need to use the correct client files. When you fire up the technic launcher, with tekkit selected click on options. The make sure you have recommended build selected, NOT development build. If it's not that then no idea. You've given absolutely no information to go on .

He probably means he just loaded the world in MC1.2.5 and saw what happenned It's worth bearing in mind that the tekkit 3.0 client is still in development and AFAIK they haven't finished deciding on/adding mods to it yet. So whatever you can or cannot get working now is a moot point. As for forestry being removed how much of a big deal it is will depend on whether the block IDs it currently uses are recycled to a new mod. If they are your map could have serious issues. Probably the only safe way to deal with those blocks is to remove them all from your world before moving the map to a new server.

AFAIK the only mod that is definitely disappearing when 3.0 is properly released is forestry and that's because the mod owner REALLY doesn't want his mod in tekkit as standard. You can probably add forestry back into a server but you'll have to be careful that none of the block IDs it origionally used have been moved over to another mod. If they have and you use a 2.1 map then just give forestry new empty IDs then there's a good chance the server will crash and burn when you try and run it. Basically, it could be pretty tricky to keep a 2.1 server going when 3.0 comes out.

Click the options button in the launcher and make sure you have recommended build selected, NOT development build.

Which engines are you using? Is it happening on one type or all types? What have you got the engine(s) pointing at? (They are pointing at something right? ) Most likely is they are either not pointing in the right direction or are steam/combustion and don't have any coal/fuel etc in them. If they are pointing the wrong way use the BC wrench on them to change their orientation. If they don't have a fuel source.... put some in.

In don't think anything is confirmed because they are waiting on some mods to get ported to 1.2.5 then need to see what's going to practically work together. You could look at what is in the current 3.0 dev build and see what's in there. Those are at least more likely to make it into the final build I would guess....

Is it just you getting lagged out in certain areas or is it everyone on the server? Also are you getting lag no matter which direction you head out from your "lab" or just one way? Since you said there are lines you can cross that cause the problem it might be that you are lagging when a certain chunk is loaded by your view distance. It might be worth walking into the area you are getting lag and typing "/debug clock" (without ""). It's a commandbook command that'll check how long it takes for the server to complete 20 ticks. That should at least help determine if it's you or the server struggling.