Windows 7+RC+userinit logon app failure

I'm working on this one customer's PC, it's an emachine, with release candidate on it. I knew there was some viruses on it, so I tried booting into safe mode, and when I logged in I got an error message saying Userinit logon app failure, that and the desktop didn't show up, that's when I thought outside the box, I opened up Task manager, started a new process, explorer, but I had to create the task with administrative priveleges, since then I've been scanning away with various antivirus, antispyware, and antimalware programs, right now it's no longer detecting anything, but it's still booting up with that blank screen without the error message of course, which may or may not be a good thing, so I was wondering if it's still the Userinit.exe file, if I can just copy the userinit file from one of the .old's, specifically a .old that had windows 7 beta on it, with the same type of OS, if I can replace the userinit.exe file in C:\Windows\System32\userinit, but that's just something I'm wondering about.