xterm/gnome-terminal/konsole hangs at creation/exit

I start a new xterm session and wish to run some jobs, however the xterm gets stuck once it is lanuched and does not send a command line prompt. Ctrl-C could help kill the hang and get back the control and I can do anything as normal. When I try to quit the current xterm with 'exit', it gets stuck again. Ctrl-C could also help kill this hang and xterm quits finally.

Everything was fine until this morning after the admin rebooted the server (RHEL6.5). I tried gnome-terminal and kde konsole, they all behave the same as xterm. Btw, the hang will not disapper no matter how long you leave it.

I also checked my .cshrc and .bashrc and source them manually, no hang happens. No modification on them recently as well.

Any idea what is going on? I'm very curious at what system is doing when I 'exit' xterm. Any hints on how to spot the backstage criminal is much appreciated.

Thanks!