I hope laying out this experience will not only bring me an answer, but will help someone else avoid this! I have W7 and Vista in a dual boot, and cannot activate both systems at once. As soon as I activate one, the other becomes unactivated. (SLIC issue... pls bear with me!) Background: Bought laptop with Vista and free W7 upgrade last summer. Since I built the Vista system up for months before recently installing W7, I want to keep Vista for awhile until my W7 system gets built up. (And might keep it beyond, as it is handy having a dual boot in case one OS goes south, you can boot into the other to troubleshoot, clean, fix, etc.) So Vista was pre-activated by Acer and I used ABR to backup the activation files before wiping Vista and reinstalling from my own nLite custom Vista disc. Then restored activation files. This was all last summer and went peachy. A few weeks ago I moved Vista to D:\ (and though I had the W7 upgrade disc), used an RTM with a good hash to install W7 in C:\. Everything booted fine as expected, with W7 unactivated, no product key or cert. Used Daz Loader to install an emulated SLIC 2.1, cert and Acer OEM key. Worked beautifully for W7, but broke my Vista activation, as the emulated SLIC loads into memory whether you boot into Vista or W7. (Wish it could load based on the choice at the multiboot screen!) So the emulated 2.1 SLIC does not match Vista's 2.0 cert, and it gives you the ole "this copy of Vista is not genuine" and "you must activate today." Reading more here, I saw in the Repository it said to run the Daz loader inside Vista too, if this happens. Tried it in regular and in safe modes, and I tried the different loader modes too, but it did no good. Vista would not activate. I uninstalled the Daz Loader and activation was restored in Vista, but of course W7 was now unactivated. Came back here for more reading. Found that loaders generally don't work in a dual boot (or often don't) and that I needed to do a hard mod -- that the 2.1 SLIC is backwards compatible with Vista and both OSs could be activated this way. Found a great BIOS mod by weinter (thanks weinter!) and flashed. So now BIOS has a 2.1 SLIC. I boot into W7 and manually install the cert and OEM key, and it is again activated and peachy.... BUT... Vista activation broke again. Was suggested I install a 2.1 cert in Vista (to match the 2.1 SLIC in the BIOS, but I thought Vista needed 2.0 and if it saw a 2.1 SLIC in the BIOS it would accept it, if 2.1 is "backwards compatible" with 2.0, but I guess it doesn't work that way). I tried this using the same acer 2.1 cert I used to activate W7. Copied to Vista's root and ran command as admin. Got the following error after a few moments: Script: c:\windows\system32\slmgr.vbs Line: 1648 Char: 9 Error: the data is invalid Code: 8007000D Source: (null) Dead end. I thought maybe if I reinstalled Vista in D:\ **with the new BIOS and it's 2.1 SLIC** that would do the trick. Even though that meant losing ALL MY PROGRAMS in Vista, I was now DETERMINED to get both OSs activated out of principle! I install Vista in D:\ and boot into it, and it's activated pretty as you please... BUT... W7 activation is now broke!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Why? Because installing Vista in D:\ made Windows run it's OWN loader, that loads a 2.0 SLIC into memory!! How do I know? Because I ran SLIC DUMP in W7, and it showed a 2.0 SLIC and no cert.... even though I have a modded BIOS with a 2.1 SLIC and proper cert!! I thought maybe Vista actually modified the BIOS, so I flashed the mod again. Booted to W7... still unactivated. Ran SLIC DUMP... showed 2.0 SLIC!! ARGH!! If a 2.1 SLIC is backwards compatible, why would Vista need to install an emulated 2.0 cert. AND... more importantly, how can Vista's install routine not see I have W7 in C:\ !!?? The emulated script should only run if I choose Vista from the multi-boot menu, but it seems to run at boot, regardless... and totally screws up W7. So I wiped the virgin Vista install, since it did no good, and restored my built-up Vista OS back to D:\, and my activated W7 back to C:\. I have not booted to Vista cause when I do, it will say it is not activated and not genuine. Can someone please tell me what I might try next on the Vista OS to make it play nice with the 2.1 SLIC in the BIOS ??? This is like activation ping pong... I get one activated and the other breaks... I know it's the SLIC issue, but there has to be a way to fix this. If I really need to install a 2.1 SLIC in Vista, then can anyone tell me why I got the error I did? And can I install that cert into Vista through a command prompt running from W7, so that I don't have to boot into Vista and break it? I feel like if I don't break it first (as the image that is there is activated, but with a 2.0 SLIC that will clash with my BIOS, should I boot into it)... I feel like if I can install the cert from outside of Vista, then boot into it with the right fix, all will be well. Any advice welcome and THANKS FOR READING.