Any warning or error messages. How far does it get before it freezes ?
You could try system restore to go back to a date when you know it was OK. May be worth running the sfc command to repair any damaged files.
Click the start orb and right click the "command prompt" option and select run as admin. Type exactly sfc /SCANNOW and press enter, note the space and capitols. Takes 45mins or so.
Being an Acer it will have a recovery partition that should allow you to restore to "out of the box" condition if needed. Did you burn a recovery disc at the start as prompted ?