I have read almost every thread regarding uninstalling modules but i haven't find my problem yet.

I have a localhost windows server and i have a custom install (not all-in-one) of odoo. Everything was ok, until I tried to uninstall a module (the accounting and the billing modules to be precise). I went to settings->modules, selected the module and pressed uninstall. The module is being uninstalled and I get no error messages come up. The result will be that I cannot see the button "uninstall" (it's been replaced with the button "install"). However the module is still there, fully functional.

As far as the database is concerned, in the table ir_module_module, the state of these 2 modules is now "uninstalled" instead of "installed".

1) Am I doing something wrong? Weren't the modules supposed to be uninstalled this way?

2) Have you ever faced a problem like this?

3) Is there a way to uninstall (or just prevent from loading) a module just by "tampering" with the database?

4) Same with (3) but "tampering" with the actual files/folders?

Thanks in advance for your help...