Plugin conflicts!

As I've tried to network-activate several WPMUD plugins, I'm being repeatedly left with only a blank screen - can't get back to the list of plugins in the Admin console. So, I have to then go manually delete the plugin, and my access to admin panel is restored. This has happened with several plugins ...

It has even happened on Pro Sites!

Can someone please assist me in figuring out why, AND how to troubleshoot this?

Thank you.