My phone was fine until the GB update. I lost the alarm function and I also lost the ability to open the Market app so yesterday I took the time to perform a factory reset. Total pita but so far everything is working again. I'll monitor to see if it stops working again as indicated by mgftp.
Hopefully you have better luck than I did.
After how quickly is went away again for me I will just use the alarm app I downloaded for free off the marketplace. It is working fine.