Just for verification, your BIOS does have the CD/DVD optical drive set as first boot? I believe on an Acer you have to click the F2 key at startup until the BIOS setup menu appears. Using the left/right arrow keys select the Boot option > enter. Use the up/down arrow keys to select the CD/DVD optical drive. Then use the F6 key (it might be a different key depending on how old your Acer is) to move the optical drive to the top of the list. Then I think you press the F10 key to save the BIOS boot order changes.
Other possibility is the recovery CDs became damaged in some way and just aren't working now. If you have bad recovery CDs and need an official Windows 7 installer, you should be able to get it from here: Official Windows 7 SP1 ISO from Digital River « My Digital Life
Download the ISO file to your desktop and then burn it to a blank DVD. You'll have to use the COA on your Acer when it comes time to validate the new install.