WPMU Dev Causing Server Errors??

I don't know what on my site has changed other than adding several of these awesome plugins, but for two days we've been having increased server errors. for 12 hours I couldn't get to the admin side of things although most of the front end of things was working fine. weird, right?

so this morning, after putting in a ticket to the host about the issue, as a last act of desperation I started deleting plugins from the site via the cpanel. all of the ones I was deleting were inactive ones, but about 10 in I was able to get into the admin part of the WP site again.

I don't get it! then I reinstalled the last plugin I'd deleted, but didn't active, and the site still works.

Have any of you ever experienced server errors because of something like this? I'm boggled. Host hasn't gotten back with a report about the problem, and of course the problem is even more intermittent now, so I don't know. The only thing that was weird last night as the "backup" server was at 100% but it wasn't thsi morning and I was still getting the errors.

I'm stumped.