A lot of people don't seem to know this. You can export any of the beta files using 1997 Beta UnrealEd and then import them using the Current UnrealEd. Now you can open the beta files using current UnrealEd.

EDIT: If the Beta UnrealEd doesn't work, then run it as an administrator.

The 1995 alpha, 1997 beta, and 1998 beta all require administrative rights so that the COM interface can be registered. This is how Unrealed communicates with the Unreal engine.

Between the time the 1998 beta leaked and Unreal went retail, Tim Sweeney removed all of the MFC dependencies and the COM interface.

The retail Unrealed no longer utilizes COM to inter-operate with the Unreal engine but ti does use something similar.

The problem is that the same GUID was used for all the COM interfaces of all the betas. This is why the 1998 Unrealed crashes after you run the executable from the 1995 alpha. When you ran the 1995 alpha, it registered the COM interface to that revision.

Even though the 1998 Unreal is in a different directory, it still is registered to the Unreal.exe from the 1995 alpha.