[R] Is this a bug in R?

[Revilla,AJ (pgt)]

Dear all,

I am trying to fit a nonlinear model with a autocorrelation term, but everytime I type in the command, I got an error message from Winwows and R closes itself.
The command line is as follows:

mod1<-nlme(V~A*exp(-B*A.O)*Vac.t.1.,data,fixed=A+B~1,random=A+B~1|ORDINAL,+
correlation=corCAR1(0.3179,~A.O|ORDINAL,TRUE),start=c(A=1.2,B=0.2))

I have already fitted this model allowing Phi to vary while optimizing, and it was fine, but as soon as I try to keep it fixed (argument "TRUE"), I simply can't

I don't get any error message from R, just a Windows error seying something like "R for windows GUI front-end has detected a problem and has to close". And that´s it, R is over!

I don't know if I am doing anything wrong, or if it has to be with my system (I have Windows XP Pro), but it looks like a bug in R.

Do you know anything else about this. Thank you very much,

Antonio