> ***  - "pkg_delete libxml2-2.6.23nb1" and "/usr/bin/make reinstall" to 
> upgrade properly
> ***  - "/usr/bin/make update" to rebuild the package and all of its 
> dependencies
> ***  - "/
> 
> When this happens I usually do pkg_delete and start over. Is this indeed 

and if it does exist:
rm -r /usr/pkgsrc/textproc/libxml2/work
the dir used to build libxml2

but/and..you could try:
cd /usr/pkgsrc/textproc/libxml2/work;make update

--Noud