Hi,
Sorry for my english,I'm french but thinks you can understand me...
I've the same problem as you but with a a101 slate.
After update and root on ics android had some troubes( Battery draining quickly, desktop hot and turning on alone...)and I've make a downgrade to HC and my screen was lock on acer...I think my solution can be run on your device.
First you can copy in your sd card a update file and download this one htttp://narod.ru/disk/47785011001.df9a2e456cbc4816e7df056b6130b9b8/Acer_AV041_A101_0.004.00_WW_GEN1-root.zip.html(in front of the adress there's a ''t''and mor because I can't post URL)
It's ics for a101
Copy update1.zip in your sd card and rename this in update.zip and reboot in recovery.update will not work until the end but it's fine.
Take off sd card from your slate and reboot in recovery,CWM should run.
In CWM make a wipe data and wipe partition,clear cache &dalvik and fix permission copy in sd card your update.zip ics for a100 and boot in recovery.Chooses apply sd card update zip then internal sd card and yes.update should be work fine.
Say me if it was work well.by