[R] anova leads to an error

[Skotara]

Dear R-list,

the following code had been running well over the last months:

       exam <- matrix(rnorm(100,0,1), 10, 10)
       gg <- factor(c(rep("A", 5), rep("B", 5)))
       mlmfit <- lm(exam ~ 1); mlmfitG <- lm(exam ~ gg)
       result <- anova(mlmfitG, mlmfit, X=~0, M=~1)

Until, all of a sudden the following error occured:

Fehler in apply(abs(sapply(deltassd, function(X) diag((T %*% X %*% 
t(T))))),  :
  dim(X) must have a positive length

I have not kept track of the changes in my R-version, so it might have 
to do with that.
Now it is: R version 2.9.0 (2009-04-17).

Does anybody know more about this error? I would help me a lot!

Thank you very much!

Nils