May I please have the crash log? To make this faster, you should open a support ticket with this issue at http://epixnetwork.us/Support/. My team will answer it asap, since I'm really busy at the moment.
I'm busy at the moment, so I suggest you open a support ticket with my team. They are knowledgeable with this kind of stuff. Support ticket link: http://epixnetwork.us/Support/
Are you 100% sure that your .minecraft was deleted? If so, hit edit profile and select "MInecraft 1.7.9". After that, click save profile and try to run minecraft. Tell me how that goes
Vanilla, eh? Use command blocks to check every single block and make sure it is there, and if it detects it is gone, create a new identical block in that location. But vanilla, heck. Your friend must be one hardcore redstoner.
Open taskmanager (ctrl+alt+del) and look at the background tasks. I had a similar issue, but I resolved it by closing high intensity programs. Possibly you are being used as a bot in DDoS. Have you recently installed any programs? If so, look for LOIC. Delete it. What may be happening is your computer is being sabotaged to to DDoS.
That is not your problem. That is the server's problem. I recommend that you should contact the server owner. As for your laptop being able to connect, it may be that your other computer is "glitched" on the server.
Try uninstalling optifine. If that doesn't work, follow the steps below:
First, backup your servers and worlds. Next, try deleting the .minecraft folder. (Remember, backup your worlds first!!!!) You can find .minecraft under C:\Users\your username here\AppData\Roaming
Dord, the problem is not on your side if you are able to connect to other servers. Even knowing that you are randomly able to connect, I still believe that it isn't your problem. Contact the server owner.