First of all lets clear something up here
RoboMX 2.07 or 2.08 there are no problems with and these are both official releases of RoboMX and are both stable. RoboMX is a chat client only.
Metis is a plugin that adds bot functions to RoboMX and has its own version numbers.
2.7b test 6 is a very common metis release but the changes in the sorce were never published and because its listed on Source Forge as an open source project under the rules of open source this release was not official, it is however fairly stable and useable.
2.8 is an official release of metis however, when it was made it had some varibles removed (things it uses in the scripts) and for that reason some scripts that worked fine on 2.7b test 6 wont work on 2.8.
Now there are two ways to fix this problem (I think this script issue is probably whats causing your trouble).
One is to get the Bide version of 2.8 which added those variables back into it and made older scripts more compatible. That can be found here:
httpss://archive.winmxworld.com/Bide&Musique/Modified%20Metis/
The second fix would be to go back to the metis 2.7test 6, keep in mind that there are some bug fixes with 2.8 and many folks say its much more stable when running the Bide version, but that I have used 2.7 for ever and have very little problems with it.
The third thing you could do is remove all of your scripts from the new set up, every game, script, any xmls in the folder (except the mxc.xml) and add them back one at a time and see which script is actually causing you problems.
Hope this helps