Windows Kernel event ID 41 error in Windows 7 or in Windows Server 2008 R2: “The system has rebooted without cleanly shutting down first”
http://support.microsoft.com/kb/2028504
Did you upgrade your system to Windows 7 or did it come with Windows 7 pre-installed?
Most Windows applications are 32-bit. They're slowly churning out 64-bit apps. As for activation issues, are you installing from the same DVD?
You can use the same key you used to activate Windows 7 64-bit if it is all contained on the same DVD rom. Follow Andre Da Costa's directions for phone activation in the following url:
http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_install/can-i-switch-my-os-from-retail-32bit-to-64bit/1e299c47-9227-4149-9a30-becbd33402f3
If you've upgraded:
http://windows.microsoft.com/en-US/windows7/32-bit-and-64-bit-Windows-frequently-asked-questions
How can I tell if my computer will
If you start your computer using a 64-bit Windows 7 installation disc or files, but your computer isn't capable of running a 64-bit version of
Windows, you'll see a
Windows Boot Manager error. You'll need to use a 32-bit
Windows 7 installation disc or files instead.