Windows 7 upgrade scrahed my computer; how do I fix it?At first, it hung and then rolled back to Vista Home Premium 64-bit. I tried again and it fully scrahed my computer (as in hung, no rollback, black screen). When I try to run it in Safe mode, I get the message that Windows cannot be installed in Safe Mode and that it will continue installation after the computer restarts. The computer restarts and gets as far as the pulsating Windows image and then the screen goes black. I am also not able to boot from a recovery CD. I have read that the registry needs to be repaired (is this correct?) but am not sure how to work around/with the black nothingness. Suggestions?I am trying to upgrade to Windows 7 Ultimate 64-bit from Vista Home Premium 64-bit. It is supposed to be compatible. I see that many get looped in the hung/rollback, but I only have a black screen .and don't know how to work with it.Thank you for the answers. I guess I'm not being very clear about my question, but I will try to reword: When I cannot even boot up in safe mode, how do I run a registry cleaner or anything in order to fix my computer? How can I get my computer to acknowledge that there is a CD or USB in use and then activate a program?Hardware Specs:Dell Studio XPS 435 MTThe Windows 7 Ultimate 64-bit is a legal copy purchased through a university retailer for students and teachers.Please advise if any other information would be helpful.