ALMOST FOOLPROOF METHOD...
Required tools:
-USB to SATA connector (or any old USB to SATA harddisk case )
- spare SATA laptop hard disk (any size...)
WIN32DISKIMAGER
FREEDOS
clnpwd.exe
Download WIN32DISKIMAGER from the web at https://sourceforge.net/projects/win32diskimager/
or have a linux system ready with DD
Download FDlite.zip from http://www.freedos.org/download/
http://www.freedos.org/download/download/FD12LITE.zip
extract and remember where the 32MB FD12LITE.img is..
download clnpwd.zip from somewhere and extract clnpwd.exe from it
take a small SATA hard disk and write the image FD12LITE to it using WINDISKIMAGER (or Linux DD...)
copy the file clnpwd.exe to the hard disk.
put the just created hard disk and put it in your ACER (5310 etc)
wait till the HD has booted, stop the install and run clnpwd once or twice to clean system and/or user password.
That's it..