Gem Error
After updating to version 0.9.1, and while everything worked fine on my iBook, gem seemed to be broken on my Debian Sarge box. Specifically, gem update spat out the following:
undefined method `refresh' for #<Hash:0x40746fa4>
Removing /usr/lib/ruby/gems/1.8/source_cache somehow solved the problem, but as to why… Beats me…

January 27th, 2007 at 10:00 pm
I had a similar problem with random errors showing up on gem - same solution. I poked around beforehand, and noticed that my source_cache was only 20k instead of a few megs like it should be. It’s entirely possible you only got a partial cache downloaded and that’s the source of errors.