Ice Cream Sandwich for the Transformer Prime was one of the most anticipated updates for one of the most anticipated tablets of recent memory. It was pushed out last week and so everyone's happy -- right? Sadly, some folks are missing out. We've received a number of reports from users who haven't been as successful as we were in updating to Android 4.0, their slates showing an "Unknown" serial number preventing the application of the update. ASUS is looking into the issue and affected users were told to perform a factory reset and, if that doesn't work, try it again and let the slate sit at the desktop for about 15 minutes. Let us know how you're faring in comments, and hit up the xda developers links for more support should you need it.