lme4/Matrix: Entry Point Not Found - how to fix?

Question

I have been using lme4 every day for quite a while.

Today, after opening R (x64 v 2.15.1), it complained that there is no package called ‘lme4’. So I re-installed it.

When I ran require(lme4) a popup was generated saying Entry Point Not Found. The procedure entry point Rf_copyListMatrix could not be location in the dynamic link library R.dll and after clicking OK the message there was an error in the R console:

Error: package ‘Matrix’ could not be loaded

So I reinstalled Matrix, after running require(Matrix) the same popup is generated followed by this error in the console

Error in inDL(x, as.logical(local), as.logical(now), ...) : 
  unable to load shared object 'C:/R/R-2.15.1/library/Matrix/libs/x64/Matrix.dll':
  LoadLibrary failure:  The specified procedure could not be found.

I have tried restarting R and rebooting the PC.

How can I fix this ?

Update: sessionInfo() gives the following:

R version 2.15.1 (2012-06-22)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United Kingdom.1252 
[2] LC_CTYPE=English_United Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

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

other attached packages:
[1] lattice_0.20-10

loaded via a namespace (and not attached): [1] grid_2.15.1

Answer 1

I have now solved this problem.

It required a minor upgrade of R from v 2.15.1 to 2.15.2