I also tried what was listed on an older post (Trouble installing package "xlsx") but the method suggested here - the following two lines of code -
debug(utils:::unpackPkgZip)
install.packages("xlsx")
This also did not work because R is throwing an error with the first line "debug". This is the error -
Error in get(name, envir = asNamespace(pkg), inherits = FALSE) :
object 'unpackPkgZip' not found
Any help would be appreciated. Thanks
Mohit