This error may state "Ethovision has detected some experiment inconsistencies." It may result either because necessary files are missing, or the experiment file is damaged.
The most likely reason for this error is that you do not have the entire experiment's folder with all the necessary components to open that experiment. If you have just the .evxt file, please note that the .evxt file by itself is not a usable file. You need the entire folder that contained it (which should also be named for the experiment). The .evxt file has an index of all of those files and folders but it does not, for example, include any tracking data.
Here's an example of what an entire experiment looks like:
As you can see, there is an .evxt file, but also lots of other files/folders. When the .evxt file is in the folder with these other files, it should open properly. Without those files, you will receive an error.
Sometimes when you zip/compress a folder and then restore it in a different location, Windows will omit any empty folders. EthoVision does expect those folders to be present, so if the only thing that is missing are empty folders, it may resolve things if you create them. Note that the External folder has a subfolder "SyncOut", and Configuration Files also has subfolders; it may be easiest to copy these from a working experiment.
Rather than copying the experiment or zipping the experiment folder, use EthoVision to create an experiment backup. In EthoVision, open the original experiment and then go on the menu to File > Make Backup. That will create an .evz file which is an experiment backup. There is an option to omit the media files (i.e. videos) which will make the file much smaller but not interfere with analysis, although if you want to recheck tracking you may want them. Then take that file to the other computer and use File > Restore Backup to create all the required files and folders.
Another possibility is that the experiment file is damaged. However, EthoVision creates a backup of this file. Try the following to use that backup: