Try to completely unisntall the ESET NOD32 anti virus. Restart the computer, and observe if the same will happen again !
1. If not, then u take a fresh copy of the same AV and again install the same. Most probably, any files that related to this AV possibly corrupt. U may use another AV (licensed) and try to install it. Also check if there are any updates available for the same application on their website
2. If the problem happens again after uninstall, then reboot the PC in Safe Mode (pressing F8) and may use “System Restore utility” to roll back to a previous known working condition. U may also run sfc / scannow command to verify that all protected Windows files are fine, scan the system for errors, and repair these errors.
U may also copy the same DLL file from another computer from the network (if exists). Remember, when copy, must take care about compatible DLL file. And register the same on system by running the REGSVR32 /u DLL_Name.dll command.
Hope it may pull out from now where u r !