there is a way to alleviate this problem and additionally smooth out the grief caused by so called "rod-babies" at the same time.
Many people might disagree but it seems(at least IMHO) the fair thing to do.

(In NON Group situations)Spread EXP ped damage percentage dealt:when a non group player weakens a monster and then someone lower level kills it,the EXP divided according to damage dealt (this will not work in a group where you have non combative characters,like enchanters and healers)

Additionally you can alter the EXP granting pattern by disallowing experience points AND loot from way higher level monsters,the SAME way it is done for way lower level ones.At the moment all higher level monsters are purple.If changing +20 levels mobs(compared to you) to not grant any XP,whether in a group or not, and vanishing the corpse and subsequent loot for ALL players it will help discourage disproportional level players grouping together.

oo dammit..i might edit the post and refine it.... it is late, i have to go to a certain someone and my mind wonders elsewhere right now,see you.

(/cast raise dead thread :repeat off)

I have an idea for an exp system that would eliminate any problems with the party exp system and parties that have large lvl gaps between members. I posted it in the suggestions forum:

http://www.daimonin.net/index.php?name=PNphpBB2&file=viewtopic&p=21079#21079