The only time I ever had an export hang on me was when there was a problem with disk space.

On Windoze, I have my .DMP files limited to <4 gigs cause winzip has a problem with files over 4 gigs.

Once I ran out of file names by doing the following...

FILE=D:\blah\dump1.dmp, D:\blah\dump2.dmp

When dump2.dmp hit 3900M, the export hung.

You may want to check disk space or quotas on the dir that you are in.
Hope this helps.