Why the 'Measured negative execution time!' error appears? (And how to deal with it?)

I am getting to know some of the microbenchmark R package's featrues. I implemented a sample code from this publication of Hadley Wickham and received an error I cannot find any precise information about and I cannot deal with. Thank you in advance for any explanation / hint etc.

An example code:

library(microbenchmark)

f <- function() NULL
microbenchmark(
  NULL,
  f()
)

Console output:

Error in microbenchmark(NULL, f()) : 
  Measured negative execution time! Please investigate and/or contact the package author.

UPDATE. Here is my seesionInfo() console output:

> sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=Polish_Poland.1250  LC_CTYPE=Polish_Poland.1250    LC_MONETARY=Polish_Poland.1250
[4] LC_NUMERIC=C                   LC_TIME=Polish_Poland.1250    

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

other attached packages:
[1] ggplot2_0.9.3.1      microbenchmark_1.3-0

loaded via a namespace (and not attached):
 [1] colorspace_1.2-4   dichromat_2.0-0    digest_0.6.3       grid_3.0.2         gtable_0.1.2       labeling_0.2      
 [7] MASS_7.3-29        munsell_0.4.2      plyr_1.8           proto_0.3-10       RColorBrewer_1.0-5 reshape2_1.2.2    
[13] scales_0.2.3       stringr_0.6.2      tools_3.0.2    

UPDATE 2. Some further information the author of the package asked me for:

• R variable R.version

  R.version _
  platform x86_64-w64-mingw32
  arch x86_64
  os mingw32
  system x86_64, mingw32
  status
  major 3
  minor 0.2
  year 2013
  month 09
  day 25
  svn rev 63987
  language R
  version.string R version 3.0.2 (2013-09-25) nickname Frisbee Sailing

• make, model and speed of the CPU in my computer:

Processor: Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz 3.70 GHz

RAM: 16,0 GB

System type: 64-bits

UPDATE 3.

I have noticed that one of the modifications of the code above does return a correct result:

> ### 1 
> f <- function(){NULL} 
> microbenchmark(NULL, f())
Error in microbenchmark(NULL, f()) : 
  Measured negative execution time! Please investigate and/or contact the package author.
> 
> 
> ### 2 
> f <- function(){ } 
> microbenchmark(NULL, f())
Error in microbenchmark(NULL, f()) : 
  Measured negative execution time! Please investigate and/or contact the package author.
> 
> 
> ### 3 
> f <- function(){NULL} 
> microbenchmark(f())
Unit: nanoseconds
 expr min lq median uq  max neval
  f()   0  1      1  1 7245   100
> 
> ### 4 
> f <- function(){ } 
> microbenchmark(f())
Error in microbenchmark(f()) : 
  Measured negative execution time! Please investigate and/or contact the package author.