Uploading the worksheet would not help as it would work as expected when we open and recalculate it.
Looks like a Prime bug in the installer for some foreign versions resulting in a broken installation. We have already seen the very same error message here:
All the OP could do (apart from the obvious procedure of completely uninstalling and then reinstalling Prime) is to open a case at PTC support - they should be able to provide a fix for this bug.
There is not enough information, but I can make some guesses and suggest possible ways to solve the problem:
1. The problem may be related to a specific worksheet or specific sequence of action, i.e. specific worksheet, or specific sequence of actions brings symbolic engine to an unresponsive state. In this case it should be reported to tech. support with this worksheet, or reproducible scenario.
2. The problem can be a one time failure. In this case it will be enough to just close all instance of Mathcad Prime or restart the computer and try again.
3. It might be an indication of a corrupted installation. In this case Mathcad Prime needs to be uninstalled and installed again.
