browser() is called incidentally (?) somewhere from inside methods::as

Hi,

Executing the following code causes the prompt to enter browser() mode.

dd<-as(Npatrick1,"list")

Called from: as(Npatrick1, "list")
Browse[1]> 

R : Copyright 2004, The R Foundation for Statistical Computing
Version 2.0.0 beta (2004-09-20), ISBN 3-900051-07-0

Some addtitional info about Npatrick1

is(Npatrick1)

[1] "Massvectorlist" "Mlist"          "List"           "list"          
[5] "vector"  

/E

Dipl. bio-chem. Witold Eryk Wolski             @         MPI-Moleculare Genetic   
Ihnestrasse 63-73 14195 Berlin                'v'    
tel: 0049-30-83875219                        /   \       
mail: witek96@users.sourceforge.net        ---W-W----    http://www.molgen.mpg.de/~wolski 
      wolski@molgen.mpg.de