The android upgrading screen is caused by cache being wiped. If its doing it on every boot then sounds like you have something set to wipe cache on every boot. As far as the boot loop I'm not sure, its working fine for me now. How exactly did u install it? Just cache or dalvik too?
Sent from my DROIDX using RootzWiki
So... After wiping and reflashing Gummy 1.2.0 and GAPPS then doing and advanced restore of my old nandroid data and Many, MANY reboots after removal of certain system and user apps (mainly live wallpapers, root browser, and rom toolbox lite since I use the pro version), the "Android is Upgrading..." issue is no longer there. All the reboots were an attempt to see where the issue was if it returned but fortunately (or unfortunately if you REALLY wanted to know where) it has not. sskmod 1.2.0 works fine. Tried flashing the .zip for that and the .zip for Apex 1.2.0 and got the bootloop again. Restored the nandroid I made before flashing those two zips then flashed the sskmod again but rebooted w/o the Apex mod. No problems. Went into CWM and flashed the Apexmod .zip separately and rebooted. Bootloop again. So it seems THAT issue is either my phone or the mod. I have a backup of the Apex 1.2.0 launcher just in case you have other ideas but I noticed that there is already a stable Apex 1.2.1 update so I'm going to do that and deal with it for now. I wish I could help more but I'm just now trying to learn the dev side of things and how to use adb and linux so I wouldn't even know where to begin to send you anything where you could look to see where the issue is if it's even possible to do that. Thanks for all the help. You and so many others on here are crazy helpful and so much patience to take the time to make these mods and then get crap from people waiting for updates or when something doesn't work for them. Again, thanks for all the effort.
Edit: Forgot to mention... Everything seems to be working fine so far even with boot manager. So I really mean it when I say I have no clue where the "Android is Upgrading..." issue came about.