update R 2.11.0，there is error when using plot(), how can I do?

a<-1:5
b<-2:6
plot(a,b)

Error in function (width, height, pointsize, record, rescale, xpinch,  :
   Graphics API version mismatch


before, R 2.10  , plot() is ok.   Now, R 2.11.0 does not work

YYou have probably an old version  of the graphics package in your 
search path.
Just look into your libraries and delete any "graphics" package that are 
not in your R_HOME/library

Uwe Ligges