ggplot2 error: "Error in as.environment(where) : 'where' is missing"

Hmm...I think it used to work before, but it gives an error now. Here is
some sample code:

=============
library(ggplot2)
Sample <- rep(c('A','B'),rep(10,2))
Vals <- sample(1:1000,20)
dataf <- as.data.frame(cbind(Sample,Vals))

myplot <- ggplot(dataf,aes(x=Vals,colour=Sample)) + geom_density()
myplot
=============

I get the following error:

"Error in as.environment(where) : 'where' is missing"

Am I doing something wrong?

thanks!



**************** sessionInfo() ***************

R version 2.15.2 (2012-10-26)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] splines   grid      stats     graphics  grDevices utils     datasets
methods   base

other attached packages:
[1] gridExtra_0.9.1       sm_2.2-4.1            imputation_2.0.1
locfit_1.5-9          TimeProjection_0.2.0  Matrix_1.0-12
timeDate_2160.97
[8] lubridate_1.2.0       gbm_2.0-8             survival_2.37-4
gplots_2.11.0         MASS_7.3-23           KernSmooth_2.23-10
caTools_1.14
[15] gdata_2.12.0          heatmap.plus_1.3      ggdendro_0.1-12
ggplot2_0.9.3.1       hgu133a.db_2.7.1      affy_1.34.0
genefilter_1.38.0
[22] biomaRt_2.12.0        org.Hs.eg.db_2.7.1    GOstats_2.22.0
graph_1.34.0          Category_2.22.0       GO.db_2.7.1
RSQLite_0.11.2
[29] DBI_0.2-5             geneplotter_1.34.0    lattice_0.20-15
annotate_1.34.1       AnnotationDbi_1.18.4  Biobase_2.16.0
BiocGenerics_0.2.0
[36] colorRamps_2.3        RColorBrewer_1.0-5    sparcl_1.0.3
gap_1.1-9             plotrix_3.4-6         som_0.3-5
pvclust_1.2-2
[43] RobustRankAggreg_1.0  impute_1.30.0         reshape_0.8.4
plyr_1.8              zoo_1.7-9             data.table_1.8.8
foreach_1.4.0
[50] foreign_0.8-53        languageR_1.4         preprocessCore_1.18.0
gtools_2.7.1          BiocInstaller_1.4.9   hash_2.2.6

loaded via a namespace (and not attached):
[1] affyio_1.24.0    bitops_1.0-4.2   codetools_0.2-8  colorspace_1.2-1
dichromat_2.0-0  digest_0.6.3     GSEABase_1.18.0  gtable_0.1.2
IRanges_1.14.4
[10] iterators_1.0.6  labeling_0.1     munsell_0.4      proto_0.3-10
RBGL_1.32.1      RCurl_1.95-4.1   reshape2_1.2.2   scales_0.2.3
stats4_2.15.2
[19] stringr_0.6.2    tools_2.15.2     tree_1.0-33      XML_3.96-1.1
xtable_1.7-1     zlibbioc_1.2.0

	[[alternative HTML version deleted]]