I had the same prob. I run a shared hosting biz (friends only) and when I set up the account in question, the storage space on the server HD was VERY small (like 25 mb or something ridiculous like that). So installing WP put me over my limit. So no upgrades.
Went to my WHM and upgraded my package to 500 mb, problem solved. Hope this helps someone out – altho i doubt it, mine was a unique situation and it was just stupidity on my part.
