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...
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.