i installed xp on its own partition and explorer was set as the deafult program for opening zip files. I deleted that installation and used xp to upgrade win2k. Now the default program is a program called enzip (which I uninstalled). Now i would like to set it back so that explorer is the default program. I tried reinstalling xp several times but that did not help.

try this
http://www.ntcompatible.com/cgi-bin/files/pickem.cgi?comprfd

thank you. that solved the problem