If you've followed this entire thread, you'll see that the "best" results (and the cases that are Most Likely to Succeed) involve installing a single version of LabVIEW with the corresponding Device Drivers. If you have a legitimate LabVIEW distribution, you should have LabVIEW, possibly some Toolkits and Modules, and a Device Driver disk, all for the same Version (in the case of the Device Driver, it might have a Fall or Spring date -- if you are using LabVIEW 2012, you should have the August 2012 or February 2013 Device Driver disk, for example).
The first step is to "start clean". This means going into Control Panel, finding the NI Software entry, and choosing "Remove All". This can take several hours (depending on the speed of the machine, and how much is installed). Reboot. Start installing LabVIEW. My recommendation is to "install in pieces, separated by Reboots". That is, install LabVIEW, reboot, install the minimum set of Toolkits and Modules you'll need, reboot, install DAQmx (if a separate installation), reboot, and lastly, install the Device Drivers that you'll need (and reboot, of course).
This can easily take half a day. However, if your installation media are valid, it should (almost always) work, with MAX running.
I've had the "pleasure" of repairing/redoing a number of LabVIEW installations over the past few years, and "learned the hard way" that it took more time to "try to fix it" one piece at a time (which rarely worked) than the above "Remove and Replace" procedure.
Please undo whatever manual file changes you made to the system. Hopefully you have the original file(s) backed up.
Then, for a minimal fix that should get all the mentioned DLLs up-to-date and in sync, please install the NI System Configuration 16.0.1 Run-Time Engine from http://www.ni.com/download/ni-system-configuration-16.0.1/6412/en/. Alternatively, or if that does not resolve the problem, then install NI System Configuration 16.0.1 (the larger "full" distribution that also includes MAX 16.0) from http://www.ni.com/download/ni-system-configuration-16.0.1/6411/en/.
The problem seemed to be caused by an old version of the "nisysapi.dll" that is a depends of the "mxrmcfg.dll" and lays in Windows\SysWOW64 on a 64bit machine. We have renamed it, replaced by the version 15.xxx copied from another machine, rebooted and purged %TMP% and trashcan. MAX can be started again." All files from SysWOW64 ? i don't think it will be a good ideea.Which one has to be renamed and with what version?
All files from %TMP% and in the trashcan. Name and version depends on your current one. Check it on another machine that has not the issue.