I read somewhere in this forum that it is a froyo issue. Before the update it did happen to me on occasion, after the update it got worse. It is suppose to be fixed in gingerbread. My solution until then is gosms pro. It actually works better than stock and gives me a signature which the stock SMS doesn't give you.
A got a Verizon rep to respond to me on twitter but as soon as I got him the rest of the Info they left for the weekend. I'll try again on monday
