PC is a refurbished Dell Dimension

PIII -- 1GHZ
256 MB RAM
20 GB HDD
Win 98 SE

Tried installing NAV 2004. Install went fine except it never asked me for a product key. Tried to activate, but screen just goes away and back to desktop. Tried all of NAV's support options (rnav, remove reg entries, files, folders, etc., reinstall Windows scripting 5.6) with no help. I uninstalled 2004 & tried to install a brand new copy of NAV 2005. Same problem. Anyone have any suggestions.

PS -- PC has a fresh load of Win98 SE. Already tried install on a clean boot. Did trend online scan, symantec online scan, spybot, adaware, all windows updates, hijack this, cwshredder.

Thanks in advance for any suggestions.