Oops, sorry. There's still a problem. Trying to pinpoint it right now.
[Edit: Update to 0.90 fixed this second error I had with 0.89. Thank you!]
Clicking the programs works now, but the "Open with" shortcuts (alt + number) still do not (same error as before: File not found.)This problem is supposed to be fixed in XnView MP 0.88. Please check and confirm the bug fix here.