I never had a problem with gmail on my transformer until the .21 firmware update. It started slow and occasional but got worse and worse. I'd tried clearing the cache and data as well as rebooting as others had suggested. But in the end no matter what I did gmail would crash typically 5-30 seconds into using it. Saturday night I uninstalled updates and haven't had a crash since. I don't know what was changed between the stock app and the most recent update, but it is allowing me to use it fine. I just spent the last hour or so going through my various mail boxes cleaning them up.