I tried every of the hotkeys, including "Esc" to close the Lister window, numeric keys [1] to [7] to change the current Lister mode, including [4] to switch to the next plugin, [Ctrl+F] and [F7] to search for a text, [F2] to update, [N] to go to the next file etc etc. Even the system-wide global hotkeys [Ctrl+C] and [Ctrl+A] do not work, although I thought before, that they work always and everywhere. All appropriate commands are still available via main menu (the commands "Select all" and "Copy" are available via context menu as well), but hotkeys are totally disabled. And it is a huge pain for me, as I use HTMLView plugin very much in my work (it is certainly plugin number 1 for me) especially in order to search and copy text fragments in HTML documents - and it is very inconvenient for me to use mouse for these operations.

I've tried virtually everything to solve the issue. For instance I restarted TC with the default wincmd.ini, also I removed HTMLview configuration files HTMLView.ini and positions.ini. In order to exclude any possible conflict with other plugins or TC settings I installed TC from the scratch in a new folder and added the only plugin HTMLView. Also I tried older versions on Total Commander (8.01, 8.51). The result was always the same: hotkeys do not work in Lister/HTMLview window.
Well, I conclude, that the problem is somehow connected to the OS MSIE (Microsoft Internet Explorer), which is used as an engine by HTMLView. In this event is it clear, that the issue should be a system-wide and is not specific to the TC-instance. But... another plugin IEView uses Internet Explorer engine too, but hotkeys still work in this plugin. Besides what could be the reason, why HTMLView worked until yesterday before and now has suddenly stopped? I've not installed any either system or MSIE update last dates.

I've found some other topics regarding similar issues at the forum during the last 10 years, but seems, that non of them suggest any solution (for instance https://www.ghisler.ch/board/viewtopic.php?t=22403 , https://www.ghisler.ch/board/viewtopic.php?t=22390 , https://www.ghisler.ch/board/viewtopic.php?t=23509 , https://www.ghisler.ch/board/viewtopic.php?t=35684 ). In some of those cases the proble was resolved by updating HTMLView to a new version, but I already use the last version 1.2.6 (18.12.2011) of the plugin.
Could anybody please suggest any solution? Thank you very much for your help.