to be honest, i've never actually had this problem

when i did a clean install i had a copy of My Documents and the Application Data folders. The application data folder is a hidden folder, but either way, my hotkeys were preserved

as for copying your hotkeys from the txt file, i'm not entirely sure how you would do that... i would have thought the option would be in the same dialog where you saved the hotkey mapping...
but if it was you wouldn't be asking

looks to me like no one actually knows the answer to the question...

it seems strange that you could save the hotkey mapping but not load it

sorry i'm not help to you, dude