Make sure you've read the SS2 Technical FAQ before you go on. Post problems in Helpdesk.

The Problem
After messing with the keybinds the Use-Mode seems to be broken as the weapon in hand fires while trying to carry out any use-mode actions.

The Solutions
1. SS2 Modmanager
Since version 0.0.4.2 the SS2 Modmanager can fix this problem automatically. Check the Tools menu.

2. Quick-solution
Load the default keybind set in the game via [Options -> Controls -> Customize Controls -> Load]. That should get you a working setup but overwrites your custom key binds.

3. Fixing key binds yourself and how to make them into a re-usable mod
If you want to fix your own keybinds that you created in SS2 you have to do it with a code-editor that can read and save the hidden line breaks in the bind-files. Use your favourite code-editor like Notepad++, PSPad, Crimson Editor, etc. Or use the somewhat less comfortable DOS-Editor built into windows:
In Windows go to [START -> Run]. Type in "edit" and hit enter.
Within the editor locate your shock2-install dir and then go to the Binds folder there.
Notice that there are always 2 bind files for each configuration in the Binds-folder. Presumably this is for the different controls in shoot- and use-mode.
The files you're looking for should look something like: "cfga000X.bnd and "cfgb000X.bnd". (Replace 'X' with a number.) You can find out which files are yours easily by opening them. In the first line of the file there's it's name used within the game. (eg "my binds", "default fps" or whatever you use.)
Now change the files like this:

In cfga000X.bnd (shoot-mode) your mouse-binds should look like this:

Code: [Select]

bind mouse1 +fire_weapon
bind mouse2 frob_object

In cfgb000X.bnd (use-mode) your mouse-binds should look like this:

Code: [Select]

bind mouse1 +drag_and_drop_mode
bind mouse2 frob_object_inv
When your done, save the files and load them in the game via [Options -> Controls -> Customize Controls -> Load].
BTW: There's a user.bnd-file in your SS2 install folder too but you don't need to bother with that. It's just the current Binds loaded and will get replaced when you load your own binds.

3. How to make your own personal binds-mod
You can assign most functions in the game. [Main menu -> Options -> Customize Controls].
To assign the psi skills, within the game hold down shift and press the appropriate F-key while the mouse pointer is over the psi power you want to assign.

When you're done with changing all the keys according to your taste and mousebinds are working you can easily make a Mod out of this that's compatible with the SS2 Modmanager. You can then use it on any new SS2 installation.
To do that simply zip up your Binds-folder and change the extension to .ss2mod.
Doubleclicking the mod will make the Modmanager recognize it. You can now activate it there at will.

Check this link for another solution to this problem: http://www.ttlg.com/forums/showthread.php?p=1615172#post1615172

Excerpt from that post:

Basically, reload a configuration file, or open the file User2.bnd in a proper text editor (Windows Notepad will not cut it here since it will break all the line breaks) and find the line:

Code: [Select]

bind mouse1 [something]

and change it to:

Code: [Select]

bind mouse1 +drag_and_drop_mode


G-Flex has reported that other keybinds are getting corrupted as well, namely:

Code: [Select]

bind ctrl +query
bind lctrl +query
bind alt +split
bind lalt +split