[texworks] Every "typesetting" finishes with "Process crashed" after last miktex update

[Ignasi]

I've been using 'official' texworks 0.4.6 with miktex on windows 8.1 
(x64) for a long time without problems.

Yesterday I made an update on my miktex system and now every press to 
"typesetting" button
finishes with "process crashed" message.

Texworks works as usual, I can edit files and it calls 
pdflatex/xelatex/lualatex as usual. Console output shows
how compilation process develops, but before showing pdf results it 
suddenly stops. Message "process crashed" is seen after
scrolling down console output.

If texworks is closed and opened again I can reload previous file and it 
shows corresponding pdf which was correctly generated.
The only problem seems to be when compilation finishes and tries to open 
pdfviewer.

If I use miktex provided texworks I've no problem with it.

I tried to reinstall texworks from 
https://drive.google.com/folderview?id=0B5iVT8Q7W44pYzBwMjFBWGdVVHM&tid=0B5iVT8Q7W44pMkNLblFjUzdQUVE 
but same problem remains.

Do you know what could be wrong?

Ignasi