@patts
The FAQ on the website covers computer shutdowns - it's because E-UAE can't start (for whatever reason: bad config file, missing ROMs, etc.), so as it exits, the system thinks the user is quitting the emulation and hence shuts down. E-UAE saves a log, so it's possible to find out what's wrong.
(If anyone can think of a better way of doing this, please let me know!)
Regarding sloooow emulation: yes, much of it is due to the configuration. Amiga Forever uses the original UAE, but it's *fast*. It took a while to figure out exactly which 'magic' options enable that kind of speed in E-UAE. The .uaerc supplied with X-Amiga just needs the relevant substitutions for your system. With everything else left at default (don't delete lines because you're not using a particular feature!) it should fly. I hope... ;-)
Amir