I'm running approximately 75-80 plugins each on 3 different sites and statpress-reloaded is a bean counter's wet dream! Spectacular!
It's the combo of certain plugins that breaks a site. No rhyme nor reason that I can see, but have had it happen enough to know the serious grief it causes.
For those that haven't experienced the trouble shooting process - you disable your plugins folder via ftp, then re-enable it and add the plugins back in one-by-one in the wp admin plugins screen. It can be a very tedious process... unless you have a pretty good hunch which plugin(s) that might be the cause of your site blowing up!
Then you start with the suspected bad boys, and disable one-by-one. You gotta love open-source software - especially for the free price in most cases!