Safe Mode and System Restore can fix startup issues in an Acer Aspire One, but if the computer won't even load the boot screen, the problem could be related to the basic input/output system (BIOS). The Acer Aspire One 110 and 150 are two models that can have BIOS-related problems that prevent the computer from booting. You can upgrade the BIOS through a USB flash drive to repair this issue. If you are able boot past the startup screen, but can't sign in to Windows, you can use Windows Advanced Boot Options to bypass startup problems.
Acer Aspire One 110 and 150
Go to the Acer website (see the Resources). Click "Support," then select "Download" from the menu on the left.
Select "Netbook" as the product family. Click "Aspire One" as the product line. Select "AOA110" or "AOA150" as the product model.
Click the "BIOS" tab. Click the download button and save the file to the desktop.
Go to the desktop when the download completes. Double-click the file to open it.
Drag-and-drop the folder to the desktop. Double-click the folder to open its contents in Windows Explorer.
Double-click the "BIOS_Acer_3310_A_AOA110 & AOA150" folder. Double-click the "Dos_Flash" folder.
Insert a blank USB flash drive into a USB slot. Drag-and-drop the "3310.fd" and "Flashit.exe" files to the flash drive.
Right-click the "3310.fd" file. Click "Rename." Change the file name to "zg5ia32.fd" and press "Enter."
Connect the AC adapter to the power jack. Hold down "Fn" and "Esc" with one hand, then press the power button with the other.
Release the "Fn" and "Esc" keys when the power indicator light comes on. Wait at least seven minutes for the system to fix the BIOS and repair the Acer Aspire One startup issues. The computer will restart automatically when the process is complete.
Turn on the computer. Press "F8" before the Windows logo appears to access the Windows Advanced Boot Options menu.
Scroll to "Last-Known Good Configuration." Press "Enter" to load Windows. If the OS fails to start up, hold down the power button for 10 seconds to turn off the computer.
Press the power button to turn the Acer Aspire One back on. Press "F8," then select "Safe Mode" from the options.
Log in to Safe Mode. Click "Start," "All Programs," "System Tools" and then "System Restore." Click "Next."
Select the last working restore point from the options. Click "Next." Click "Finish" to run System Restore and recover the Acer Aspire One to a previous state.
If the Acer Aspire One still experiences problems starting up, turn on the computer and hold down "Fn" and "F10" on the boot screen to run Acer eRecovery Management. Click "Restore Operating System to Factory Defaults" to erase the hard drive and reinstall the OS. Keep in mind that this step will require you to lose all of your personal files.