rails c : [FATAL] failed to allocate memory

I am getting this error when trying to run my rails app :

[FATAL] failed to allocate memory

This is on a new mac book air with lion. It use开发者_如何学Pythond to run ok, I don't really know what I changed...

I also get this error when doing rake db:drop :

[BUG] Segmentation fault
ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-darwin11.0.1]

-- control frame ----------
c:0001 p:0000 s:0002 b:0002 l:000498 d:000498 TOP   
---------------------------

-- C level backtrace information -------------------------------------------

[NOTE]
You may have encountered a bug in the Ruby interpreter or extension libraries.
Bug reports are welcome.
For details: http://www.ruby-lang.org/bugreport.html

Abort trap: 6

someone knows how I can fix this? Thanks!