[R] memory problems when combining randomForests

[Eleni Rapsomaniki]

Hello

I've just realised attachments are not allowed, so the data for the example in
my previous message is:

pos.df=read.table("http://www.savefile.com/projects3.php?fid=6240314&pid=847249&key=119090",
header=T)

neg.df=read.table("http://fs07.savefile.com/download.php?pid=847249&fid=9829834&key=362779"",
header=T)

And my last two questions (promise!): 
The first is related to the order of columns (ie. explanatory variables). I get
different order of importance for my variables depending on their order in the
training data. Is there a parameter I could fiddle with (e.g. ntree) to get a
more stable importance order?

And finally, since interactions are not implemented, is there another method I
could use in R to find dependencies among categorical variables? (lm doesn't
accept categorical variables).

Many thanks
Eleni Rapsomaniki
Birkbeck College, UK