Thanks for the suggestions. Dependency walker showed about the last thing that was accessed before hanging was KMW_DLL. Kensington Mouseworks. I almost dismissed that as insignificant. But I went to add/remove programs and removed it (I still have the installer if it was really needed). That fixed things. Now Opera starts right up in Windows 2000 SP4. And the mouse still works perfectly well, as far as I can tell. So Kensington Mouseworks 6.11 is, at least on my system, somehow incompatible with KernelEx. I'll just mention the other things I noted. It said that apphelp.dll and userenv.dll were not found. I guess apphelp.dll is not actually needed. There's a userenv.dll in KernelEx, I got it recognized by adding KernelEx to the system path -- not sure if that's appropriate, but it didn't seem to hurt anything. I also see someone else wrote a userenv.dll, so I'm a little fuzzy as to whether that should or shouldn't be on the system somewhere. My GDI32.dll had file date 1998-01-22 but link date 2012-09-01. That seemed suspicious. It reported the same version as the original, too. I ended up extracting a clean one from the CAB file. So I may have backleveled a patch I've forgotten about. But it's working fine, so far as I can tell. I never had heard of dependency walker before. Thanks for telling me about it. For backup, I resorted to DFSee and closed my C drive to a USB stick. The big question is whether I'll be able to find the USB stick when it's needed. I didn't think I had installed the Windows installer 2.0, but when I tried to run the installer it said it was already on the system. Unicows.dll is 1.1.3790.0, per Windows Explorer. There's another unicows file, unicows.pdb, sitting next to it. I'm not sure what that's for or if it really came from Microsoft. Anyway, everything is working great right now. Mouseworks was apparently the major issue, and removing it has made my KernelEx work much, much better. Thanks. -- walt