Windows 7 - Not able to create Windows Defender Offline Beta flash drive

Hi, I'm new, so please excuse my ignorance. I'm not even sure that I'm in the correct forum...feel free to advise.

Anyway, Microsoft Security Essentials gave me a message basically telling me that I needed to run Windows Defender Offline Beta by creating, in my case, a flash drive. I've tried multiple attempts on an uninfected machine, but each time I insert the flash drive to create it, it downloads fine etc, but when I get to the point where I need to click on 'Update file definitions' (or whatever it says), I get the message that says, "Virus and spyware definitions update failed". I've read the 'frequently asked questions' and did lots of other research, but the it simply won't let me create the flashdrive. I eventually used tdsskiller and got rid of the Trojan.DOS/Alureon.A, but I wanted to create the flash drive for future use in case the problem occurs again. Like I said, I'm trying to create it from a different uninfected machine, but I continue to get the same "...definitions update failed" and therefore can't run the scan. I've spent a lot of hours trying to get this to work. Any ideas would be greatly appreciated.

Lastly, is there a way for me to set it up to where answers to my post(s) come to my email address so I'll know to come to this forum to read? I assume I select 'Notification Type: Instant email notification" below, but I noticed it was listed under the area where I click "Submit New Thread". I just want to make sure that I receive any of your advice. Again, pardon my ignorance, but I'll figure it out.

Thanks to all!!!