Few months ago I changed my Win7 orb using this software. But it changed only the explorer.exe in C:\Windows. To solve that, I copied explorer.exe from there to C:\Windows\system32 and C:\Windows\SysWOW64 (Probably a bad idea).

Things were working fine until a few days ago, it started giving me problems while copying. Sometimes, when I copy/paste, It works fine but sometimes it stays on that dialog box which looks like it is doing pre-copying things like counting number of files/file size etc. But its not. It stays on that screen forever. Now if I try to close it, title changes to cancelling but rest stays the same.

If I try to close it too many times, explorer.exe crashes. And its not related to file-size. It may crash for 4Mb file and work fine for 10Gb file but some other time, it'll do the opposite.

Is there any way to reset my explorer.exe and Is this because of explorer.exe or something else

PS: I forgot to take backup of explorer.exe.

PS2: I didn't install any software or downloaded anything that could harm my computer.

EDIT

I tried System Restore and SFC /scannow but they didn't help.