glm: NA/NaN/Inf in foreign function call

Dear all,
I am running the glm function (family: Poisson) in R and most of the time it
works fine. But sometimes, with large data sets, I get the following error
message:
Error: NA/NaN/Inf in foreign function call (arg 1) 

What puzzles me most about this is the fact that there are no missing values
in my vectors at all- so where do the missing values come from? Could this
be related to the size of the vectors I use?

Thanks

Janine

------------------------------------------
Peace cannot be kept by force. It can only be achieved through
understanding. 
Albert Einstein  

Janine Illian
lecturer in statistics
SIMBIOS
School of Computing and Advanced Technologies
University of Abertay Dundee
Bell Street
Dundee, DD1 1HG 
Scotland, UK
Tel: +44-(0)1382-308488
Fax: +44-(0)1382-308537