Ok, I think I've found a possible solution. You have to clear the data and cache in your "gmail" and "gmail storage" applications. Settings>applications>manage applications> and then go to both the gmail and gmail storage apps and clear data and cache (don’t worry about the dire warnings, it’s not like your e-mail or anything are deleted). That seems to have fixed it for me at least temporarily. Haven’t had a chance to truly test it out in a back and forth email exchange, but I was able to forward an email with no problem. So far so good. Please post your experience after trying this, if you’d like to share.