Changes to path alias from nodes and image nodes are not registered

I use Drupal CVS and I just installed the image module, which works without any problems.

However, I now have this weird problem occurring:

I create a node of any type (story, page, book, flexinode, etc.) or an image node, assign to it an url alias in the "Path Alias" field and I publish it. The node or image is created without a problem, with the correct url alias.

Then, I go back to the node or image and edit it: I change the url alias. I click submit, and I am redirected to the old url alias. Going back into edit mode, I see that the value that shows up in the "Path Alias" field is the correct, new url alias that I'd previously entered. However, clicking on submit again (without any other changes) still brings me to the old url alias.

Going to the Url Alias admin page, and looking up the node or image through the node id, I see that the old alias is the one that shows up. Checking directly in the database confirms this.

So, the fact that the url alias was changed is acknowledged in the node/image edit page itself, but the change never makes it to the url alias database table.

Since this started happening after installing the image module, I went to the modules admin panel and disabled it. Then I tried to submit the new url again from the node edit page, and this time it worked. I then reactivated image.module, and unfortunately the same misbehaviour started reappearing at once, so I suppose it's a conflict between the path and image module.

I hope this can be solved, since the image module is really useful, and having to manually change the url alias from the url alias admin page instead of directly in the node is time-wasting.