Hi Frank,
Jumping in to help; kemical may be sleeping or eating dinner as it's the end of his Sunday there. It's good you uninstalled your Trend Micro as kemical suggests. However, uninstalling Windows Defender and reinstalling can be tricky, as it's part of the W7 OS and can be tricky to get out.
You may have 2 problems if you can't boot the burned ISO file of the new WD (Windows Defender). Typically, Windows Defender is
NOT a bootable disc or usb stick. That's probably why it's not booting up as you are expecting when the computer starts up!
Since there's no boot setup on the ISO disc, it jumps to the next device in your BIOS boot preference order which is probably your Hard Drive with W7.
If you don't see a Black & White screen on startup that says:
"...hit any key to boot from DVD disc" or similar, you probably have a stand-alone executeable file (a bin file) on that ISO disc you burned with IMGBURN. The best thing to do if that is the case, is to COPY that file from your DVD disc once you have booted into your W7 desktop. You can then use Windows Explorer to launch the copied executable file that's now residing on a folder on your hard drive such as Downloads or on your W7 desktop as an icon. Either way, use Windows Explorer and double-click the executable file
mssstool64. With any luck, the installer program will launch and reinstall your WD and you're all set to go!
If it still doesn't work, you'll have to use a special tool such as
REVO uninstaller to go into your Registry and attempt to remove all traces of WD from before your reinstall attempt with the new ISO file you downloaded. kemical might have some other ideas, but short of tweaking your Registry manually you may never be able to accomplish that. Plus, it's super-risky if you don't have expert skills using the Registry (only with Regedit.exe, not 3rd party tools).
If this occurs, your best bet is to do a complete W7 reset or reinstallation from
Factory RECOVERY MEDIA (DVD or USB) if you have it. This is the only way to 100% guarantee you'll ever get WD working again on that computer IMO.
At least you have some things to try until kemical gets back with you.
One other thing, on your IMGBURN dashboard, if you are burning ISO files you downloaded to DVD disc, the option you want to select is:
"WRITE IMAGE FILES TO DISC", Ok?
@kemical: Ross, hope you don't mind me jumping in here.
Best,
<<<BBJ>>>