Technic is just as bad with single player bug wise. But there should be no problem running single player on tekkit. Where did it ever say that you cannot use tekkit single player?
My bets are on that you have two servers hosted on the same port, but if you want to check computer craft, then just cut the (CC) mod files and put them in a place you can get back to, and then try the server and see if it works.
Hi, you were helping me with trying to reduce lag, and suggested checking my java. I've done all that, and, if you're willing, I'd still like your help please Thank you.