Yea i'd say it's yur pc. Well i'd say dont use Plus! for now I'm afraid i'm not sure what else to recommend, an official tester or Patchou might be better at thelping u at this point, sry.
u can alwasy pm them (just surf the other posts and look for the "official tester" badge, or just wait till tmr, they visit the board for sure and give ya a reply
If your Messenger still crashes with Messenger Plus! 3.61 (the last version released), please email me at mplus@patchou.com and we'll check that out together.