EDIT: I did search this thread for the term: ACER Composite ADB interface ... I did not see the 'SOLVED' post on the last page
You can download the usb drivers from acer: (these are not for ICS)
v1.00.0524 2011/10/06 (*acer claims that this is newer, even through the version is less)
v1.06.1500 2011/08/08 (*this is what I installed)
When windows says a driver cannot be found.
If you go into device manager and choose the reinstall or update the driver you can manually point it the files extracted, from one of the archives above.
Choose: 'ACER Composite ADB interface'
**NOTE: this will not give access to internal or sd storage, but it will allow access through adb like normal.