installing m4 ssd on mac mini

I installed a crucial m4 ssd along with the stock drive in my 2011 2.3ghz mac mini. after putting it in i installed osx 10.7.4 on it. when i booted it up, which took almost 2 minutes, i found that it was slower than any hard drive i have ever owned. black magic disk tests had it writing at 100MB/s and reading at 500 MB/s however it would stall or freeze on simple tasks like opening a folder. I have erased and reinstalled osx 3 times and that hasn't fixed it. when i run it as an external drive it is not slow at all. when i run it in my macbook pro 2.8ghz mid 2009 it is lighting fast. its only when its installed in the mac mini is when its slow. ive tried it in both spots in the logic board and its still slow. any body have any ideas?