There is no need to change computer's language settings, it's not relevant.
start game first, then start HR should solve game path issue.
HR will never affect battle.net launcher, it's not relevant too. I think it's related with other reason like your .net runtime environment is messed up.
You can try to re-install .net framework 3.5 sp1 and .net framework 4.0, it may solve your issue.
Also make sure your anti-virus software doesn't block hearthranger.exe.