PDF and PS output

I'm using R 2.0 on Redhat Linux 9.  When I try to produce PDF or PS
output, the files are corrupted -- they won't open in Acroread, xpdf,
ggv, and on attempting to convert to PNG, I get message "This file has
corrupted %%EOF marker."  Perhaps I am just doing something wrong.  I
did:

pdf()
hist(unlist(foo.bar))

I have no trouble viewing the output in Xwindows.

Thanks,
Hans