I just discovered that the IMSCore plugin, which manages a set of core functions for Sean Donahoe's Internet Marketing Success Centre plugins such as pingfresh and promotemepro, causes an error when using WPMU Dev Dashboard to install plugins.
Clicking install for any plugin returns an error with the install button going purple and saying "Error". I can switch off the IMSCore plugin and install works fine, and tried this on two different sites with no other plugins activated.
I can send you a copy of the IMSCore plugin to try it if you want at your end and hopefully help resolve the conflict. I need these two IMSC plugins work, and can contact the other guys too of course but I thought this would be the best way to start...it's not a large file to send, so tell me where, if that works..?
workaround is to switch it off while managing wpmudev plugins but would be nice to fix this.