The latest release of 7-zip (open source, small, effective, fast) is quite satisfactory.
What do you mean by that "open files from here correctly"? Unpacking errors are almost impossible if the archive is correct and so is your computer. But, it is possible that the packed files are with an error in themselves.

To eliminate possible content issues:
- put only one map file (fbl). Download it from other source (different uploader) or other provider (Here/TT). For example from [Only registered and activated users can see links. ] then from [Only registered and activated users can see links. ]
Test.
- then add the rest of the files, one by one, test after each, (fpa, then fsp, then poi, then buildings)... etc

If you encounter a problem after a few files, try only with that file (next to the map).
- If there is still a problem - that file is defective
- If the problem is lost and reappears after adding a few files, then the problem is in the device.
Either its processor can't handle that amount of data (in fact its cache registers are defective), or the memory chip is messy.


And after all, it is quite possible that your device is not working properly.

I have two WinCE devices, one is quite old and weak, has a KIA clean package (480x272) on it and the other is newer with CIVIC (800x480).
I have no such problems.