Mail Crashing When Adding Recipeint Addresses

Question

SL 10.6.1 -- Late 2007 Macbook -- Santa Rosa CD2 2.2 GHz, Seagate 320 HD 7200 RPM, 4 GB RAM
When holding down the Apple key on the keyboard, so that I can select and add multiple addressees from the address book, Mail will crash -- spinning beach ball for 10-seconds, addressing function does not allow selecting any more addressees from the address list, then Mail crashes. Upon Mail restart, original unsent email is intact, ready to be addressed, but addresses that were being selected when Mail crashed do not show up in BCC field of unsent mail.
Reselect same addresses for the second time -- find that if I select fewer addresses (say 5-7) and hit BCC button at top of addressing pane, those selected addresses will transfer over to unsent email with no problem -- repeat process for next group of addressees -- 5-7 at a time -- until all addresses have been selected and BCCd to pending email -- crashing seems to be occurring because of selecting too many addressees before hitting BCC button.
Just went into the Address Book app get-info, and selected 32-bit -- if this does not fix this problem, then will do the same for Mail -- force it to run in a 32-bit mode.

Answer 1

No Plaxo installed -- stock install and apps, nothing fancy or 3rd party, per se.
I crash Mail MANY times a day, because of this bug -- am considering downgrading to Leopard, as I rely on Mail to function without crashing, and without the resulting annoyance and hassle.