Sounds like your zone files for whichever zone your main is in could be corrupt - a fresh install would probably fix it, but barring that you could try replacing just the zonename.s3d, zonename_chr.s3d, and zonename_obj.s3d files, where zonename is the zone's name.
There is a much rarer server-side bug that can prevent you from logging into certain zones, but you'll want to rule out bad files on your end first. A simple way you can figure out if your files are the problem is by bringing another character to the same zone - if you crash when zoning in then you have some bad files and the issue should be easily fixable by replacing them. If other characters can access the zone without issue, then you've got a more serious problem and you'll probably want to put in a forum petition, and read this thread for more info:
http://www.project1999.com/forums/sh...d.php?t=250004