hmmm looks to me like a problem that wengi had some days ago and described it in the german part of this forum.
FastJack came with the solution for it, so gratz to him if this helps!
I believe you have bash installed, if so check your /opt/etc/profile and remove the following code:
restart putty and it should work again hopefully
PS1="[\u@\h \W]$ "
export PS1 PATH LD_LIBRARY_PATH
hope that helps!