Are you getting this error when you launch the mantra renderer?

Warning: invalid .mplay_lock file detected
Warning: invalid .mplay_lock file detected
mantra: Could not open imager

The problem is caused by your firewall….

Set full permissions to Houdini/bin/mantra.exe and it will disappear.

I've added a note about this on the community wiki:

http://odforce.net/wiki/index.php/IncompatibleSoftware [odforce.net]

Thanks!

BTW, which firewall software were you using?

I'm using safety.net firewall….

I wouldn't say its incompatible…. but the mplayer calls mantra as a subroutine I guess….. and it only asks to set permissions for the mplayer… not mantra.exe…. and all we need to do is set the permissions for mnatra.exe to full and it works….

I'm just happy I solved it..it was driving me insane!

I just ran into this, thanks a bunch, Norton was causing this issue for me in H16.5, the firewall was the cause of the issue.