having repeated trouble with MySQL and Snow Leopard - Unable to lock ./ibdata1, error: 35

Question

I don't know very much about server maintenance and am trying to learn by managing my own Mac. I'm running a local rails application with a MySQL database (5.5.9). All has been well for a long time UNTIL I attempted to start a new rails project. At that time, I ran bundle install, which updated my mysql gem from 0.2.6 to 0.3.6. Ever since then, or I'm associating with that (it may be that I also installed RVM around that time), I can't startup my MySQL server. I get the following error:

Unable to lock ./ibdata1, error: 35

repeatedly. I've tried fixing with:

mv ibdata1 ibdata1.bak
cp -a ibdata1.bak ibdata1

which works (reference: http://cglreport.zhenhua.info/2008/08/mysql-error-unable-to-lock-ibdata1.html) (I have to do it on a few other files too), but it only works for a while. When I restart, or periodically the problem comes back. What's going on ? This doesn't seem to be a reasonable solution to me. Ideas? Thanks!