We've noticed errors from several users when trying to open a file that uses a code page instead of Unicode encoding. The specific error is:
No mapping for the Unicode character exists in the target multi-byte code page. (Exception from HRESULT: 0x80070459)
This problem is caused by us using a file reading API Microsoft provides which apparently can only read Unicode files. Any files saved in code pages can't be opened using it.
We have found another way to open files that doesn't have this problem, and have it ready to go for the next version (v1.2).
Actipro Software Support