I only have 1 mod installed and it's a helicopter mod but when I made a neather portal I tried to go back home, but even though I went through the same portal it sent me to a wierd location under ground. When I tried to dig my way up it suddenly said saving chunks and then it crashed. It's happened 3 times all right away. Also the login screen is full of wierd words that kinda look like code, instead of the usual list of updates. Please help.
Also, are you running the lastest version (1.2 or greater?)