Any thoughts as to why this is breaking some of my sites

Yesterday I spent the day researching caching plugins. I am running MU and domain mapping. I installed Quick Cache as I am not that technical with the innards of WP and this seemed to be the safest route for someone in my shoes. I gained some significant speed increases and all seemed to be working great. I also installed WP Minify and thought I had everything working there also. Later in the day, I found that my sites were displaying properly in IE, but were showing nothing but a bunch of weird symbols, numbers, punctuation in Chrome. I tried clearing the cache. I tried manually clearing Minify. Neither worked. Oddly, however, this only affected about half of my sites. I deactivated Minify and the problem still existed. I deactivated Quick Cache and the problem was fixed. I waited and tried reactivating Quick Cache this morning, and again same effect (Minify not enabled at this point).

However, the speed difference in my sites is HUGE and I need to find a way to get something like this back running on my sites. Is there any suggestions out there with good documentation on how to set this up for a caching/minify, etc plugin that will get the job done without having to be a configuration guru on Multisite running domain mapping? Are there any thoughts on why this would have negatively affected some of my sites, but not all?