Problems with gem system update

Im fairly new to ruby and have been playing around with rails, merb and
other gems. today i ran sudo gem update --system and im getting the
following error.
Any idea what can be causing this?

Updating RubyGems
WARNING: RubyGems 1.2+ index not found for:
http://merbivore.com

RubyGems will revert to legacy indexes degrading performance.
Updating metadata for 120 gems from http://gems.rubyforge.org/

complete
ERROR: While executing gem … (Gem::RemoteFetcher::FetchError)
bad response Not Found 404 (http://merbivore.com/Marshal.4.8)

Thanks in advance!

maybe because there is no merbivore gems repo any more?
try:

gem sources

then remove the other sources.

gem sources -r http://merbivore.com

if that doenst work then you can manually remove them

vi ~/.gemrc


:update_sources: true
:sources:

hth

/dc