[R] Corrupt R installation?

[Ralf B]

I installed the lattice package, and got an error that R was not able
to remove the previous version of lattice. Now my installation seems
to be currupt, even affecting other packages. I am getting this error
when loading TTR:

> library(TTR)
Loading required package: xts
Loading required package: zoo
Error in loadNamespace(i, c(lib.loc, .libPaths())) :
  there is no package called 'lattice'
In addition: Warning messages:
1: package 'TTR' was built under R version 2.10.1
2: package 'xts' was built under R version 2.10.1
3: package 'zoo' was built under R version 2.10.1
Error: package 'zoo' could not be loaded

My question now is, is there a way to manually remove lattice (or
whats left from it) ? Or do I have to go through the process of
completely re-installing? What do you guys do to prevent such a
situation - is there an easy way to secure a R installation?

Ralf