GoVoice has had quite the ride lately. For us, the Google Voice client has not worked properly since about v2.0 as we had problems with it crashing and no push notifications. Since then, we've been talking with Nick Yu, GoVoice's developer and watching him work through these many problems, a lot related to how complicated Microsoft's v1.0 Push system can be for developers.
We're happy to finally report that v2.5 is now live in Marketplace and working for us: it's faster, push notifications work and no crashing, in other words: perfect. There is also a new feature: "If your phone didn't receive text for some reason (low battery, Q full), GoVoice will resend up to 10 times."
Our advice? Uninstall your current version, soft reset and then go and re-download from the Marketplace. It may also help to unregister your device with GVMax.com for notifications and then have it re-set up. Grab it here.