I ran into a very strange problem recently: I'm administrating Mandriva Linux in a networked setup where users authenticate via NIS. We noticed that pdflatex simply stalls with no error messages and output. All we get is the following:
This is pdfTeX, Version 3.1415926-2.3-1.40.12 (TeX Live 2011/Mandriva)
restricted \write18 enabled.
**
It doesn't accept any commands or produce any output that we can see. We get the same behavior if we try running it on a file, as in pdflatex <filename>
Using a local user (as opposed to an NIS user) account, I was able to compile LaTeX files with no problem, so this seems related to NIS somehow. The weird thing is, we have one NIS user who doesn't face this problem and can compile LaTeX files normally.
Has anybody seen this before? Are there known solutions/workarounds? Is there a way for me to investigate further to help you answer this question?
Thanks
EDIT: My answer below is based on Martin Schröder's suggestion.

strace; it will show you where it hangs. – Martin Schröder Oct 4 '12 at 12:51/home/david/would just look in that directory, but a TEXINPUTS segment/home/david//specifies that directory and all subdirectories should be recursively searched for file input. – David Carlisle Oct 4 '12 at 16:16