[R] numerical or not?

[Laetitia Schmid]

Hi,
I've had a little problem for several weeks now. It is annoying and  
therefore I will ask for help now:
When I write a script with several iterations, I make it write out a  
text file to save the data during the run. For example I write:
if (i %% 25) write.table(output,"temporary_output.txt")
Later on, when I read in this output and want to calculate things, R  
complains that x is not numeric.
I read it in with the following command:
dat1<-read.table("temporary_output.txt",header=TRUE).
It seems that R is saving my temporary output as a list.
What is here wrong? And how can I do it better?

Thanks.
Laetitia